<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2020 Workiva-->
<!--r:dcb3e3cd-cf59-4577-b603-b6b151a72bad,g:a86e8db6-6b23-4abf-a8fb-11d121aa50df-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/Cover" xlink:type="simple" xlink:href="prth-20200930.xsd#Cover"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/Cover" xlink:type="extended" id="ic1d9e9d98f4641958bb178232eb6e061_Cover"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/CondensedConsolidatedBalanceSheets" xlink:type="simple" xlink:href="prth-20200930.xsd#CondensedConsolidatedBalanceSheets"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/CondensedConsolidatedBalanceSheets" xlink:type="extended" id="i9125313b191948bb940150131c8a5cfb_CondensedConsolidatedBalanceSheets"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="simple" xlink:href="prth-20200930.xsd#CondensedConsolidatedBalanceSheetsParenthetical"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="extended" id="ib66d622ad253443d8267952bb3f76f46_CondensedConsolidatedBalanceSheetsParenthetical"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/CondensedConsolidatedStatementsofOperationsUnaudited" xlink:type="simple" xlink:href="prth-20200930.xsd#CondensedConsolidatedStatementsofOperationsUnaudited"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/CondensedConsolidatedStatementsofOperationsUnaudited" xlink:type="extended" id="i48f84b58a4574bb5accea34820bc2a4a_CondensedConsolidatedStatementsofOperationsUnaudited"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited" xlink:type="simple" xlink:href="prth-20200930.xsd#CondensedConsolidatedStatementsofCashFlowsUnaudited"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited" xlink:type="extended" id="i06ddaf42348a4222a8f54ab4125c343a_CondensedConsolidatedStatementsofCashFlowsUnaudited"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/BASISOFPRESENTATIONANDSIGNIFICANTACCOUNTINGPOLICIES" xlink:type="simple" xlink:href="prth-20200930.xsd#BASISOFPRESENTATIONANDSIGNIFICANTACCOUNTINGPOLICIES"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/BASISOFPRESENTATIONANDSIGNIFICANTACCOUNTINGPOLICIES" xlink:type="extended" id="i67026865dd9b488fa7cf6b7e41a34b06_BASISOFPRESENTATIONANDSIGNIFICANTACCOUNTINGPOLICIES"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/BASISOFPRESENTATIONANDSIGNIFICANTACCOUNTINGPOLICIESPolicies" xlink:type="simple" xlink:href="prth-20200930.xsd#BASISOFPRESENTATIONANDSIGNIFICANTACCOUNTINGPOLICIESPolicies"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/BASISOFPRESENTATIONANDSIGNIFICANTACCOUNTINGPOLICIESPolicies" xlink:type="extended" id="ic7570d77663742bc97f7ad43449afb05_BASISOFPRESENTATIONANDSIGNIFICANTACCOUNTINGPOLICIESPolicies"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/SALEOFBUSINESS" xlink:type="simple" xlink:href="prth-20200930.xsd#SALEOFBUSINESS"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SALEOFBUSINESS" xlink:type="extended" id="ib2f6a0d5265e4690980b6ed0c1362f6d_SALEOFBUSINESS"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/DiscontinuedOperationsandDisposalGroupsTables" xlink:type="simple" xlink:href="prth-20200930.xsd#DiscontinuedOperationsandDisposalGroupsTables"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/DiscontinuedOperationsandDisposalGroupsTables" xlink:type="extended" id="id19cb16af6c84f54b4f3ba3ec56477e8_DiscontinuedOperationsandDisposalGroupsTables"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/SALEOFBUSINESSNarrativeDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#SALEOFBUSINESSNarrativeDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SALEOFBUSINESSNarrativeDetails" xlink:type="extended" id="i8372e51feb6d465c82755acddf4ac1e2_SALEOFBUSINESSNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_b529696d-91a9-4905-ae06-d29041a98101" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DisposalGroupNotDiscontinuedOperationConsideration_84d0d23b-4607-43d3-84a9-f7500708021d" xlink:href="prth-20200930.xsd#prth_DisposalGroupNotDiscontinuedOperationConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_b529696d-91a9-4905-ae06-d29041a98101" xlink:to="loc_prth_DisposalGroupNotDiscontinuedOperationConsideration_84d0d23b-4607-43d3-84a9-f7500708021d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DisposalGroupNotDiscontinuedOperationWorkingCapitalAdjustmentPaidInCash_ea488bef-4292-4034-9303-b448114b6108" xlink:href="prth-20200930.xsd#prth_DisposalGroupNotDiscontinuedOperationWorkingCapitalAdjustmentPaidInCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_b529696d-91a9-4905-ae06-d29041a98101" xlink:to="loc_prth_DisposalGroupNotDiscontinuedOperationWorkingCapitalAdjustmentPaidInCash_ea488bef-4292-4034-9303-b448114b6108" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_62077437-6236-491c-a3f1-405058a8c685" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_b529696d-91a9-4905-ae06-d29041a98101" xlink:to="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_62077437-6236-491c-a3f1-405058a8c685" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DisposalGroupTaxEffectOfDisposalGroup_187058a7-ae77-4ef0-bbea-9255879cc1dd" xlink:href="prth-20200930.xsd#prth_DisposalGroupTaxEffectOfDisposalGroup"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_b529696d-91a9-4905-ae06-d29041a98101" xlink:to="loc_prth_DisposalGroupTaxEffectOfDisposalGroup_187058a7-ae77-4ef0-bbea-9255879cc1dd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountReturnOfCapital_b553bd9b-d692-41ea-a49c-c5a0ab418ebe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PartnersCapitalAccountReturnOfCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_b529696d-91a9-4905-ae06-d29041a98101" xlink:to="loc_us-gaap_PartnersCapitalAccountReturnOfCapital_b553bd9b-d692-41ea-a49c-c5a0ab418ebe" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_08ab6f9c-0a57-4b98-ad2f-006e06f4425d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_b529696d-91a9-4905-ae06-d29041a98101" xlink:to="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_08ab6f9c-0a57-4b98-ad2f-006e06f4425d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ReductionOfOperatingLeasesFutureMinimumPaymentsDue_b2c169e0-d200-45d6-8649-a07edb900d48" xlink:href="prth-20200930.xsd#prth_ReductionOfOperatingLeasesFutureMinimumPaymentsDue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_b529696d-91a9-4905-ae06-d29041a98101" xlink:to="loc_prth_ReductionOfOperatingLeasesFutureMinimumPaymentsDue_b2c169e0-d200-45d6-8649-a07edb900d48" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_fd7d4577-a96e-426d-98df-11d32f0396fe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_b529696d-91a9-4905-ae06-d29041a98101" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_fd7d4577-a96e-426d-98df-11d32f0396fe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_6c10a10b-2c1b-481b-bc26-97c29a28131e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_fd7d4577-a96e-426d-98df-11d32f0396fe" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_6c10a10b-2c1b-481b-bc26-97c29a28131e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6c10a10b-2c1b-481b-bc26-97c29a28131e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_6c10a10b-2c1b-481b-bc26-97c29a28131e" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6c10a10b-2c1b-481b-bc26-97c29a28131e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_70df9b19-fcea-4b9e-aefe-4729f1efc16b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_6c10a10b-2c1b-481b-bc26-97c29a28131e" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_70df9b19-fcea-4b9e-aefe-4729f1efc16b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_9694603b-7bab-40ad-ba1c-c4a55181863e" xlink:href="prth-20200930.xsd#prth_PriorityRealEstateTechnologyLLCPRETMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_70df9b19-fcea-4b9e-aefe-4729f1efc16b" xlink:to="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_9694603b-7bab-40ad-ba1c-c4a55181863e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitAxis_9f7dd3fb-8dea-4197-a426-67c2f7d47223" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_fd7d4577-a96e-426d-98df-11d32f0396fe" xlink:to="loc_us-gaap_ReportingUnitAxis_9f7dd3fb-8dea-4197-a426-67c2f7d47223" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_9f7dd3fb-8dea-4197-a426-67c2f7d47223_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReportingUnitAxis_9f7dd3fb-8dea-4197-a426-67c2f7d47223" xlink:to="loc_us-gaap_ReportingUnitDomain_9f7dd3fb-8dea-4197-a426-67c2f7d47223_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_f3bb4909-7d5e-477b-a13f-5ac6880fd759" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReportingUnitAxis_9f7dd3fb-8dea-4197-a426-67c2f7d47223" xlink:to="loc_us-gaap_ReportingUnitDomain_f3bb4909-7d5e-477b-a13f-5ac6880fd759" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_IntegratedPartnersRentPaymentComponentMember_319ad7ea-0206-4c5d-a67d-1083b862ccb2" xlink:href="prth-20200930.xsd#prth_IntegratedPartnersRentPaymentComponentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_f3bb4909-7d5e-477b-a13f-5ac6880fd759" xlink:to="loc_prth_IntegratedPartnersRentPaymentComponentMember_319ad7ea-0206-4c5d-a67d-1083b862ccb2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_b5bf971f-a4d2-455d-a8d2-156c6df87084" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_fd7d4577-a96e-426d-98df-11d32f0396fe" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_b5bf971f-a4d2-455d-a8d2-156c6df87084" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_b5bf971f-a4d2-455d-a8d2-156c6df87084_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_b5bf971f-a4d2-455d-a8d2-156c6df87084" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_b5bf971f-a4d2-455d-a8d2-156c6df87084_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_bc2babfe-8378-4175-9e2e-fe7a095d4cf6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_b5bf971f-a4d2-455d-a8d2-156c6df87084" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_bc2babfe-8378-4175-9e2e-fe7a095d4cf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_SyndicateOfLendersMember_58ac6de6-b0d0-41c8-a3d0-12b4b007c968" xlink:href="prth-20200930.xsd#prth_SyndicateOfLendersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_bc2babfe-8378-4175-9e2e-fe7a095d4cf6" xlink:to="loc_prth_SyndicateOfLendersMember_58ac6de6-b0d0-41c8-a3d0-12b4b007c968" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_2a30afd4-a680-4bca-90d7-38212b0fa0cf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_fd7d4577-a96e-426d-98df-11d32f0396fe" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_2a30afd4-a680-4bca-90d7-38212b0fa0cf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_2a30afd4-a680-4bca-90d7-38212b0fa0cf_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_2a30afd4-a680-4bca-90d7-38212b0fa0cf" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_2a30afd4-a680-4bca-90d7-38212b0fa0cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_116ac5bd-8908-481f-88eb-9b7ecd92ff54" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_2a30afd4-a680-4bca-90d7-38212b0fa0cf" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_116ac5bd-8908-481f-88eb-9b7ecd92ff54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_c69ebdde-0295-4275-abe6-ce577d715148" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_116ac5bd-8908-481f-88eb-9b7ecd92ff54" xlink:to="loc_us-gaap_LineOfCreditMember_c69ebdde-0295-4275-abe6-ce577d715148" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_d3627168-9ac2-481d-a431-e6f6611ea090" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_fd7d4577-a96e-426d-98df-11d32f0396fe" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_d3627168-9ac2-481d-a431-e6f6611ea090" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_d3627168-9ac2-481d-a431-e6f6611ea090_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_d3627168-9ac2-481d-a431-e6f6611ea090" xlink:to="loc_us-gaap_EquityComponentDomain_d3627168-9ac2-481d-a431-e6f6611ea090_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_2742a7b1-b279-4dd7-a3bd-fc4cc8682db5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_d3627168-9ac2-481d-a431-e6f6611ea090" xlink:to="loc_us-gaap_EquityComponentDomain_2742a7b1-b279-4dd7-a3bd-fc4cc8682db5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParentMember_08e710bc-12b1-4811-87ef-67279eaac3bf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_2742a7b1-b279-4dd7-a3bd-fc4cc8682db5" xlink:to="loc_us-gaap_ParentMember_08e710bc-12b1-4811-87ef-67279eaac3bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_3180f349-e021-45db-8000-a7ec30b76443" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_2742a7b1-b279-4dd7-a3bd-fc4cc8682db5" xlink:to="loc_us-gaap_NoncontrollingInterestMember_3180f349-e021-45db-8000-a7ec30b76443" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/SALEOFBUSINESSScheduleofSaleDetailsDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#SALEOFBUSINESSScheduleofSaleDetailsDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SALEOFBUSINESSScheduleofSaleDetailsDetails" xlink:type="extended" id="ie63f85fc721b43fb98709aa0e6d001e7_SALEOFBUSINESSScheduleofSaleDetailsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_1f415566-e941-4277-bc6c-3db426b29f01" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DisposalGroupNotDiscontinuedOperationConsiderationBeforeWorkingCapitalAdjustmentPaidInCash_4b54f6e0-d0a6-4ac8-98f3-eb088102727c" xlink:href="prth-20200930.xsd#prth_DisposalGroupNotDiscontinuedOperationConsiderationBeforeWorkingCapitalAdjustmentPaidInCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_1f415566-e941-4277-bc6c-3db426b29f01" xlink:to="loc_prth_DisposalGroupNotDiscontinuedOperationConsiderationBeforeWorkingCapitalAdjustmentPaidInCash_4b54f6e0-d0a6-4ac8-98f3-eb088102727c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DisposalGroupNotDiscontinuedOperationWorkingCapitalAdjustmentPaidInCash_5851e286-c966-4e29-b9fa-fcba8c9d010a" xlink:href="prth-20200930.xsd#prth_DisposalGroupNotDiscontinuedOperationWorkingCapitalAdjustmentPaidInCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_1f415566-e941-4277-bc6c-3db426b29f01" xlink:to="loc_prth_DisposalGroupNotDiscontinuedOperationWorkingCapitalAdjustmentPaidInCash_5851e286-c966-4e29-b9fa-fcba8c9d010a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DisposalGroupNotDiscontinuedOperationConsideration_a892a3d9-98ae-41c9-a52f-44e5673e813b" xlink:href="prth-20200930.xsd#prth_DisposalGroupNotDiscontinuedOperationConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_1f415566-e941-4277-bc6c-3db426b29f01" xlink:to="loc_prth_DisposalGroupNotDiscontinuedOperationConsideration_a892a3d9-98ae-41c9-a52f-44e5673e813b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DisposalGroupNoteDiscontinuedOperationTransactionCosts_4c553d7b-9c18-473e-91f9-04ed07a5e40b" xlink:href="prth-20200930.xsd#prth_DisposalGroupNoteDiscontinuedOperationTransactionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_1f415566-e941-4277-bc6c-3db426b29f01" xlink:to="loc_prth_DisposalGroupNoteDiscontinuedOperationTransactionCosts_4c553d7b-9c18-473e-91f9-04ed07a5e40b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationNoncurrentAbstract_47b84254-8b0e-4446-93c9-e4b6ba221947" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationNoncurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_1f415566-e941-4277-bc6c-3db426b29f01" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationNoncurrentAbstract_47b84254-8b0e-4446-93c9-e4b6ba221947" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DisposalGroupNotDiscontinuedOperationIntangibleAssets_181668b3-9cdf-4f0a-be84-6dce47a9774e" xlink:href="prth-20200930.xsd#prth_DisposalGroupNotDiscontinuedOperationIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationNoncurrentAbstract_47b84254-8b0e-4446-93c9-e4b6ba221947" xlink:to="loc_prth_DisposalGroupNotDiscontinuedOperationIntangibleAssets_181668b3-9cdf-4f0a-be84-6dce47a9774e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DisposalGroupNotDiscontinuedOperationOtherAssetsNetOfObligations_442d2cfc-5f24-4d58-80c9-827465e74d14" xlink:href="prth-20200930.xsd#prth_DisposalGroupNotDiscontinuedOperationOtherAssetsNetOfObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationNoncurrentAbstract_47b84254-8b0e-4446-93c9-e4b6ba221947" xlink:to="loc_prth_DisposalGroupNotDiscontinuedOperationOtherAssetsNetOfObligations_442d2cfc-5f24-4d58-80c9-827465e74d14" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DisposalGroupNotDiscontinuedOperationsGoodwill_1adbe136-48a0-4cd1-9556-98d54ee3f23f" xlink:href="prth-20200930.xsd#prth_DisposalGroupNotDiscontinuedOperationsGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_1f415566-e941-4277-bc6c-3db426b29f01" xlink:to="loc_prth_DisposalGroupNotDiscontinuedOperationsGoodwill_1adbe136-48a0-4cd1-9556-98d54ee3f23f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DisposalGroupNotDiscontinuedOperationOtherIntangibleAssets_6f7446b7-411b-42c2-b5fd-481f0b17660d" xlink:href="prth-20200930.xsd#prth_DisposalGroupNotDiscontinuedOperationOtherIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_1f415566-e941-4277-bc6c-3db426b29f01" xlink:to="loc_prth_DisposalGroupNotDiscontinuedOperationOtherIntangibleAssets_6f7446b7-411b-42c2-b5fd-481f0b17660d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_1bb966a7-d22a-4052-b14b-01be49df726a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_1f415566-e941-4277-bc6c-3db426b29f01" xlink:to="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_1bb966a7-d22a-4052-b14b-01be49df726a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_b12ea05e-4b60-45fb-bacc-70dc2134ea52" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_1f415566-e941-4277-bc6c-3db426b29f01" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_b12ea05e-4b60-45fb-bacc-70dc2134ea52" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_cbe4e7b9-7cf3-4991-b557-332599cdee04" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_b12ea05e-4b60-45fb-bacc-70dc2134ea52" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_cbe4e7b9-7cf3-4991-b557-332599cdee04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_cbe4e7b9-7cf3-4991-b557-332599cdee04_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_cbe4e7b9-7cf3-4991-b557-332599cdee04" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_cbe4e7b9-7cf3-4991-b557-332599cdee04_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_541c6c0b-52bd-4ecb-a5d9-8a73acf0bf98" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_cbe4e7b9-7cf3-4991-b557-332599cdee04" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_541c6c0b-52bd-4ecb-a5d9-8a73acf0bf98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_07584240-633e-420e-b0fb-ce0e3976d725" xlink:href="prth-20200930.xsd#prth_PriorityRealEstateTechnologyLLCPRETMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_541c6c0b-52bd-4ecb-a5d9-8a73acf0bf98" xlink:to="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_07584240-633e-420e-b0fb-ce0e3976d725" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitAxis_decd1a40-baa9-454f-88fa-2f02afb2ad7a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_b12ea05e-4b60-45fb-bacc-70dc2134ea52" xlink:to="loc_us-gaap_ReportingUnitAxis_decd1a40-baa9-454f-88fa-2f02afb2ad7a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_decd1a40-baa9-454f-88fa-2f02afb2ad7a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReportingUnitAxis_decd1a40-baa9-454f-88fa-2f02afb2ad7a" xlink:to="loc_us-gaap_ReportingUnitDomain_decd1a40-baa9-454f-88fa-2f02afb2ad7a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_09e1a404-096e-4f66-8af3-02fb8dc2c71b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReportingUnitAxis_decd1a40-baa9-454f-88fa-2f02afb2ad7a" xlink:to="loc_us-gaap_ReportingUnitDomain_09e1a404-096e-4f66-8af3-02fb8dc2c71b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_IntegratedPartnersRentPaymentComponentMember_dc77be3c-5652-4b35-9f7c-b946bc73aa83" xlink:href="prth-20200930.xsd#prth_IntegratedPartnersRentPaymentComponentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_09e1a404-096e-4f66-8af3-02fb8dc2c71b" xlink:to="loc_prth_IntegratedPartnersRentPaymentComponentMember_dc77be3c-5652-4b35-9f7c-b946bc73aa83" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/SALEOFBUSINESSScheduleofProFormaInformationDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#SALEOFBUSINESSScheduleofProFormaInformationDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SALEOFBUSINESSScheduleofProFormaInformationDetails" xlink:type="extended" id="i2192fa0433024dec8973f12ee1dc32c9_SALEOFBUSINESSScheduleofProFormaInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_7c1ad72b-6a97-42c0-a54b-112b9ad57ff3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_89735c0c-7444-4635-a00b-3f1e6641d507" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_7c1ad72b-6a97-42c0-a54b-112b9ad57ff3" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_89735c0c-7444-4635-a00b-3f1e6641d507" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_3f829265-70a7-48db-848d-bbdcb5617ae7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_7c1ad72b-6a97-42c0-a54b-112b9ad57ff3" xlink:to="loc_us-gaap_OperatingIncomeLoss_3f829265-70a7-48db-848d-bbdcb5617ae7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_fabbf06e-bf1c-4791-b049-bd3caec1b047" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_7c1ad72b-6a97-42c0-a54b-112b9ad57ff3" xlink:to="loc_us-gaap_ProfitLoss_fabbf06e-bf1c-4791-b049-bd3caec1b047" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_38c5c99b-1137-419c-880a-430b1b545f8c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_7c1ad72b-6a97-42c0-a54b-112b9ad57ff3" xlink:to="loc_us-gaap_NetIncomeLoss_38c5c99b-1137-419c-880a-430b1b545f8c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDiluted_b6238eb5-22be-404a-861f-f157b23c1730" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareBasicAndDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_7c1ad72b-6a97-42c0-a54b-112b9ad57ff3" xlink:to="loc_us-gaap_EarningsPerShareBasicAndDiluted_b6238eb5-22be-404a-861f-f157b23c1730" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_EffectiveIncomeTaxRateExcludingGainOnBusinessDispositionPercent_890c18a0-52dc-48b8-b533-37f7562f52df" xlink:href="prth-20200930.xsd#prth_EffectiveIncomeTaxRateExcludingGainOnBusinessDispositionPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_7c1ad72b-6a97-42c0-a54b-112b9ad57ff3" xlink:to="loc_prth_EffectiveIncomeTaxRateExcludingGainOnBusinessDispositionPercent_890c18a0-52dc-48b8-b533-37f7562f52df" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_48de23a5-d9c5-4035-9200-cee3dfd4d0f6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_7c1ad72b-6a97-42c0-a54b-112b9ad57ff3" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_48de23a5-d9c5-4035-9200-cee3dfd4d0f6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_b6291269-6b1e-4732-bef7-5df59e3595ed" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_7c1ad72b-6a97-42c0-a54b-112b9ad57ff3" xlink:to="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_b6291269-6b1e-4732-bef7-5df59e3595ed" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_071ff800-7cf4-4744-9513-78115809ea7c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_7c1ad72b-6a97-42c0-a54b-112b9ad57ff3" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_071ff800-7cf4-4744-9513-78115809ea7c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_6b5791d7-0b74-49c2-9def-ea905a078530" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_071ff800-7cf4-4744-9513-78115809ea7c" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_6b5791d7-0b74-49c2-9def-ea905a078530" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6b5791d7-0b74-49c2-9def-ea905a078530_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_6b5791d7-0b74-49c2-9def-ea905a078530" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6b5791d7-0b74-49c2-9def-ea905a078530_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_bd6f27e0-ba63-4a6e-acf1-ec7e5685c0cd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_6b5791d7-0b74-49c2-9def-ea905a078530" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_bd6f27e0-ba63-4a6e-acf1-ec7e5685c0cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_2a2366ec-3e0f-499a-9f1c-18fb71cc139b" xlink:href="prth-20200930.xsd#prth_PriorityRealEstateTechnologyLLCPRETMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_bd6f27e0-ba63-4a6e-acf1-ec7e5685c0cd" xlink:to="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_2a2366ec-3e0f-499a-9f1c-18fb71cc139b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitAxis_a1a322ae-625d-4599-8c3d-08733aca28b2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_071ff800-7cf4-4744-9513-78115809ea7c" xlink:to="loc_us-gaap_ReportingUnitAxis_a1a322ae-625d-4599-8c3d-08733aca28b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_a1a322ae-625d-4599-8c3d-08733aca28b2_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReportingUnitAxis_a1a322ae-625d-4599-8c3d-08733aca28b2" xlink:to="loc_us-gaap_ReportingUnitDomain_a1a322ae-625d-4599-8c3d-08733aca28b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_3c03f295-4b7c-48b3-bec6-6098f4f0d6e6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReportingUnitAxis_a1a322ae-625d-4599-8c3d-08733aca28b2" xlink:to="loc_us-gaap_ReportingUnitDomain_3c03f295-4b7c-48b3-bec6-6098f4f0d6e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_IntegratedPartnersRentPaymentComponentMember_a92fa042-cc1e-4f49-ac48-09562d993c37" xlink:href="prth-20200930.xsd#prth_IntegratedPartnersRentPaymentComponentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_3c03f295-4b7c-48b3-bec6-6098f4f0d6e6" xlink:to="loc_prth_IntegratedPartnersRentPaymentComponentMember_a92fa042-cc1e-4f49-ac48-09562d993c37" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/REVENUES" xlink:type="simple" xlink:href="prth-20200930.xsd#REVENUES"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/REVENUES" xlink:type="extended" id="i5bdbfbe854d84fb59f090181e96c3db0_REVENUES"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/REVENUESTables" xlink:type="simple" xlink:href="prth-20200930.xsd#REVENUESTables"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/REVENUESTables" xlink:type="extended" id="i1f0e9748ca4b483c9de82bdfd8f7c444_REVENUESTables"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/REVENUESDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#REVENUESDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/REVENUESDisaggregationofRevenueDetails" xlink:type="extended" id="i682f678644644fc2bd080e80508790ca_REVENUESDisaggregationofRevenueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_3e306708-41b5-4cf8-a9ac-425fa0aeda02" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_bb78e45e-c605-44f5-bcaf-5f2396afe8bc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3e306708-41b5-4cf8-a9ac-425fa0aeda02" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_bb78e45e-c605-44f5-bcaf-5f2396afe8bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_aff90dd4-ce26-432e-a15c-583bea1e47d0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3e306708-41b5-4cf8-a9ac-425fa0aeda02" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_aff90dd4-ce26-432e-a15c-583bea1e47d0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_f513033c-8ad1-49b2-bc7b-199fedb45894" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_aff90dd4-ce26-432e-a15c-583bea1e47d0" xlink:to="loc_srt_ProductOrServiceAxis_f513033c-8ad1-49b2-bc7b-199fedb45894" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_f513033c-8ad1-49b2-bc7b-199fedb45894_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_f513033c-8ad1-49b2-bc7b-199fedb45894" xlink:to="loc_srt_ProductsAndServicesDomain_f513033c-8ad1-49b2-bc7b-199fedb45894_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_440302f9-3060-4f1d-8953-c6227c48683d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_f513033c-8ad1-49b2-bc7b-199fedb45894" xlink:to="loc_srt_ProductsAndServicesDomain_440302f9-3060-4f1d-8953-c6227c48683d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_MerchantCardFeesMember_3dbe5ce3-d2a6-43bd-b625-c3a08cb662b6" xlink:href="prth-20200930.xsd#prth_MerchantCardFeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_440302f9-3060-4f1d-8953-c6227c48683d" xlink:to="loc_prth_MerchantCardFeesMember_3dbe5ce3-d2a6-43bd-b625-c3a08cb662b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_OutsourcedServicesAndOtherServicesMember_77b9dd8d-a1b6-4ea4-ad2e-63e5ba0b10d4" xlink:href="prth-20200930.xsd#prth_OutsourcedServicesAndOtherServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_440302f9-3060-4f1d-8953-c6227c48683d" xlink:to="loc_prth_OutsourcedServicesAndOtherServicesMember_77b9dd8d-a1b6-4ea4-ad2e-63e5ba0b10d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_EquipmentSalesMember_dd78ca5a-bd27-4062-9dcc-24f256e26705" xlink:href="prth-20200930.xsd#prth_EquipmentSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_440302f9-3060-4f1d-8953-c6227c48683d" xlink:to="loc_prth_EquipmentSalesMember_dd78ca5a-bd27-4062-9dcc-24f256e26705" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/REVENUESBalanceSheetInformationDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#REVENUESBalanceSheetInformationDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/REVENUESBalanceSheetInformationDetails" xlink:type="extended" id="i10533a1322a44dc58b7ebd709f085081_REVENUESBalanceSheetInformationDetails"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/REVENUESNarrativeDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#REVENUESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/REVENUESNarrativeDetails" xlink:type="extended" id="i152039f6d466400eb4a86e6fd867c1c5_REVENUESNarrativeDetails"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/NONCONTROLLINGINTERESTS" xlink:type="simple" xlink:href="prth-20200930.xsd#NONCONTROLLINGINTERESTS"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/NONCONTROLLINGINTERESTS" xlink:type="extended" id="iae12f9b47511428da7ff1e26dd2f292c_NONCONTROLLINGINTERESTS"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/NONCONTROLLINGINTERESTSYapStoneDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#NONCONTROLLINGINTERESTSYapStoneDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/NONCONTROLLINGINTERESTSYapStoneDetails" xlink:type="extended" id="id50b92c3a33f47d8b5bb63580a87ebf8_NONCONTROLLINGINTERESTSYapStoneDetails">
    <link:loc xlink:type="locator" xlink:label="loc_prth_ScheduleofAssetAcquisitionLineItems_097595bb-ad2a-4d60-98b5-a52487a269f4" xlink:href="prth-20200930.xsd#prth_ScheduleofAssetAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PaymentsForAssetAcquisitions_a1e3e9fb-5687-4651-a1cf-51407a2f5b04" xlink:href="prth-20200930.xsd#prth_PaymentsForAssetAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_097595bb-ad2a-4d60-98b5-a52487a269f4" xlink:to="loc_prth_PaymentsForAssetAcquisitions_a1e3e9fb-5687-4651-a1cf-51407a2f5b04" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_52128fc5-6799-4652-90b9-e908ad8d5d40" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_097595bb-ad2a-4d60-98b5-a52487a269f4" xlink:to="loc_us-gaap_MinorityInterest_52128fc5-6799-4652-90b9-e908ad8d5d40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_AssetAcquisitionSoftwareLicenseAgreement_9207e3fe-f6d1-4639-8b6b-5636eae73793" xlink:href="prth-20200930.xsd#prth_AssetAcquisitionSoftwareLicenseAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_097595bb-ad2a-4d60-98b5-a52487a269f4" xlink:to="loc_prth_AssetAcquisitionSoftwareLicenseAgreement_9207e3fe-f6d1-4639-8b6b-5636eae73793" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_AssetAcquisitionServiceAgreement_93c5cae9-9cd0-4150-9cdb-3c5112efa4af" xlink:href="prth-20200930.xsd#prth_AssetAcquisitionServiceAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_097595bb-ad2a-4d60-98b5-a52487a269f4" xlink:to="loc_prth_AssetAcquisitionServiceAgreement_93c5cae9-9cd0-4150-9cdb-3c5112efa4af" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_6bb71787-b6fc-4993-afab-ed1b191d9ba0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_097595bb-ad2a-4d60-98b5-a52487a269f4" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_6bb71787-b6fc-4993-afab-ed1b191d9ba0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_GainLossOnDispositionOfBusinessAttributableToNoncontrollingInterest_cc19cac0-f258-41ca-a5e9-c21593146c00" xlink:href="prth-20200930.xsd#prth_GainLossOnDispositionOfBusinessAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_097595bb-ad2a-4d60-98b5-a52487a269f4" xlink:to="loc_prth_GainLossOnDispositionOfBusinessAttributableToNoncontrollingInterest_cc19cac0-f258-41ca-a5e9-c21593146c00" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ScheduleOfAssetAcquisitionTable_b945cc79-f941-4bbe-8bff-c8878499e0f0" xlink:href="prth-20200930.xsd#prth_ScheduleOfAssetAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_097595bb-ad2a-4d60-98b5-a52487a269f4" xlink:to="loc_prth_ScheduleOfAssetAcquisitionTable_b945cc79-f941-4bbe-8bff-c8878499e0f0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_AssetAcquisitionAxis_6eddacdf-f30e-4f34-8f34-fd7602349450" xlink:href="prth-20200930.xsd#prth_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleOfAssetAcquisitionTable_b945cc79-f941-4bbe-8bff-c8878499e0f0" xlink:to="loc_prth_AssetAcquisitionAxis_6eddacdf-f30e-4f34-8f34-fd7602349450" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_AssetAcquisitionDomain_6eddacdf-f30e-4f34-8f34-fd7602349450_default" xlink:href="prth-20200930.xsd#prth_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_prth_AssetAcquisitionAxis_6eddacdf-f30e-4f34-8f34-fd7602349450" xlink:to="loc_prth_AssetAcquisitionDomain_6eddacdf-f30e-4f34-8f34-fd7602349450_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_AssetAcquisitionDomain_e06444fa-d818-4da5-8a50-5b921b49e51d" xlink:href="prth-20200930.xsd#prth_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_prth_AssetAcquisitionAxis_6eddacdf-f30e-4f34-8f34-fd7602349450" xlink:to="loc_prth_AssetAcquisitionDomain_e06444fa-d818-4da5-8a50-5b921b49e51d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_YapStoneIncMember_b5dfe363-9745-472a-83a6-4b4e586ceb16" xlink:href="prth-20200930.xsd#prth_YapStoneIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_AssetAcquisitionDomain_e06444fa-d818-4da5-8a50-5b921b49e51d" xlink:to="loc_prth_YapStoneIncMember_b5dfe363-9745-472a-83a6-4b4e586ceb16" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_578e4b35-b036-4dda-81c1-c2dac559d584" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleOfAssetAcquisitionTable_b945cc79-f941-4bbe-8bff-c8878499e0f0" xlink:to="loc_dei_LegalEntityAxis_578e4b35-b036-4dda-81c1-c2dac559d584" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_578e4b35-b036-4dda-81c1-c2dac559d584_default" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_578e4b35-b036-4dda-81c1-c2dac559d584" xlink:to="loc_dei_EntityDomain_578e4b35-b036-4dda-81c1-c2dac559d584_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_c5684c95-ea9f-4c36-a54e-ee4185dd3fa0" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_578e4b35-b036-4dda-81c1-c2dac559d584" xlink:to="loc_dei_EntityDomain_c5684c95-ea9f-4c36-a54e-ee4185dd3fa0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_56702d5d-3518-42dd-a1fe-380bd3da6df0" xlink:href="prth-20200930.xsd#prth_PriorityRealEstateTechnologyLLCPRETMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_c5684c95-ea9f-4c36-a54e-ee4185dd3fa0" xlink:to="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_56702d5d-3518-42dd-a1fe-380bd3da6df0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_ee46ec63-1e1f-43a4-b289-2842189c9da2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleOfAssetAcquisitionTable_b945cc79-f941-4bbe-8bff-c8878499e0f0" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_ee46ec63-1e1f-43a4-b289-2842189c9da2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_ee46ec63-1e1f-43a4-b289-2842189c9da2_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_ee46ec63-1e1f-43a4-b289-2842189c9da2" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_ee46ec63-1e1f-43a4-b289-2842189c9da2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1dd0fb58-8e35-4f9c-b071-b9a3fed190bb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_ee46ec63-1e1f-43a4-b289-2842189c9da2" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1dd0fb58-8e35-4f9c-b071-b9a3fed190bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_139a6550-9304-44e0-80a3-ec691ef50f2d" xlink:href="prth-20200930.xsd#prth_PriorityRealEstateTechnologyLLCPRETMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1dd0fb58-8e35-4f9c-b071-b9a3fed190bb" xlink:to="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_139a6550-9304-44e0-80a3-ec691ef50f2d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitAxis_f163e8bd-8d4e-4721-b4ed-5be68ec8e9e6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleOfAssetAcquisitionTable_b945cc79-f941-4bbe-8bff-c8878499e0f0" xlink:to="loc_us-gaap_ReportingUnitAxis_f163e8bd-8d4e-4721-b4ed-5be68ec8e9e6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_f163e8bd-8d4e-4721-b4ed-5be68ec8e9e6_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReportingUnitAxis_f163e8bd-8d4e-4721-b4ed-5be68ec8e9e6" xlink:to="loc_us-gaap_ReportingUnitDomain_f163e8bd-8d4e-4721-b4ed-5be68ec8e9e6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_ead44010-bbe9-4dfb-bf96-832cbbe1da0f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReportingUnitAxis_f163e8bd-8d4e-4721-b4ed-5be68ec8e9e6" xlink:to="loc_us-gaap_ReportingUnitDomain_ead44010-bbe9-4dfb-bf96-832cbbe1da0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_IntegratedPartnersRentPaymentComponentMember_7dd361d6-ef03-489d-989e-2f428eb714e3" xlink:href="prth-20200930.xsd#prth_IntegratedPartnersRentPaymentComponentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_ead44010-bbe9-4dfb-bf96-832cbbe1da0f" xlink:to="loc_prth_IntegratedPartnersRentPaymentComponentMember_7dd361d6-ef03-489d-989e-2f428eb714e3" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/SETTLEMENTASSETSANDOBLIGATIONS" xlink:type="simple" xlink:href="prth-20200930.xsd#SETTLEMENTASSETSANDOBLIGATIONS"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SETTLEMENTASSETSANDOBLIGATIONS" xlink:type="extended" id="i120ec96d6e3b4b1bb087f0c3421e6ad8_SETTLEMENTASSETSANDOBLIGATIONS"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/SETTLEMENTASSETSANDOBLIGATIONSTables" xlink:type="simple" xlink:href="prth-20200930.xsd#SETTLEMENTASSETSANDOBLIGATIONSTables"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SETTLEMENTASSETSANDOBLIGATIONSTables" xlink:type="extended" id="ied02f4756a664f70ac3b3f10dd5070be_SETTLEMENTASSETSANDOBLIGATIONSTables"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/SETTLEMENTASSETSANDOBLIGATIONSDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#SETTLEMENTASSETSANDOBLIGATIONSDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SETTLEMENTASSETSANDOBLIGATIONSDetails" xlink:type="extended" id="i312a26e276274bd19f261ae7b7cea543_SETTLEMENTASSETSANDOBLIGATIONSDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ae151309-0919-457c-bb51-78c1c6dccda0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_MerchantReservesHeldBySponsorBanks_2e18b0b0-a761-4d9f-b7ed-415c61afa7ac" xlink:href="prth-20200930.xsd#prth_MerchantReservesHeldBySponsorBanks"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ae151309-0919-457c-bb51-78c1c6dccda0" xlink:to="loc_prth_MerchantReservesHeldBySponsorBanks_2e18b0b0-a761-4d9f-b7ed-415c61afa7ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SettlementAssetsCurrent_8853c09a-57d3-43e8-924e-07ca96fe8889" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SettlementAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ae151309-0919-457c-bb51-78c1c6dccda0" xlink:to="loc_us-gaap_SettlementAssetsCurrent_8853c09a-57d3-43e8-924e-07ca96fe8889" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SettlementLiabilitiesCurrent_7f380148-7a18-4bbc-9a44-a80d6a569b2a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SettlementLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ae151309-0919-457c-bb51-78c1c6dccda0" xlink:to="loc_us-gaap_SettlementLiabilitiesCurrent_7f380148-7a18-4bbc-9a44-a80d6a569b2a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_42148bc4-d1cb-485d-aa75-eea23aca682e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ae151309-0919-457c-bb51-78c1c6dccda0" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_42148bc4-d1cb-485d-aa75-eea23aca682e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_5777da1a-d2d6-4a6a-9f3a-ff6837c87994" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_42148bc4-d1cb-485d-aa75-eea23aca682e" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_5777da1a-d2d6-4a6a-9f3a-ff6837c87994" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_5777da1a-d2d6-4a6a-9f3a-ff6837c87994_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_5777da1a-d2d6-4a6a-9f3a-ff6837c87994" xlink:to="loc_us-gaap_ReceivableTypeDomain_5777da1a-d2d6-4a6a-9f3a-ff6837c87994_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_e9d94b5c-861c-40a6-bca6-3536e512daa2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_5777da1a-d2d6-4a6a-9f3a-ff6837c87994" xlink:to="loc_us-gaap_ReceivableTypeDomain_e9d94b5c-861c-40a6-bca6-3536e512daa2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_CardSettlementsDueFromMerchantsMember_aad6a3f1-7ec1-4727-baa0-7054f573cbe4" xlink:href="prth-20200930.xsd#prth_CardSettlementsDueFromMerchantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_e9d94b5c-861c-40a6-bca6-3536e512daa2" xlink:to="loc_prth_CardSettlementsDueFromMerchantsMember_aad6a3f1-7ec1-4727-baa0-7054f573cbe4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_CardSettlementsDueFromProcessorsMember_27cb958d-6762-41b9-b68d-17ebc83bc0d2" xlink:href="prth-20200930.xsd#prth_CardSettlementsDueFromProcessorsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_e9d94b5c-861c-40a6-bca6-3536e512daa2" xlink:to="loc_prth_CardSettlementsDueFromProcessorsMember_27cb958d-6762-41b9-b68d-17ebc83bc0d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_fe2b99fe-31a9-4043-8dd4-622a46078e28" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_42148bc4-d1cb-485d-aa75-eea23aca682e" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_fe2b99fe-31a9-4043-8dd4-622a46078e28" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_fe2b99fe-31a9-4043-8dd4-622a46078e28_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_fe2b99fe-31a9-4043-8dd4-622a46078e28" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_fe2b99fe-31a9-4043-8dd4-622a46078e28_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_61915c3c-a515-4e80-9de9-79b188ef7cc7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_fe2b99fe-31a9-4043-8dd4-622a46078e28" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_61915c3c-a515-4e80-9de9-79b188ef7cc7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_CardSettlementsDueToMerchantsMember_62e1f953-5e4f-45e7-9cef-bfb1f66e95e7" xlink:href="prth-20200930.xsd#prth_CardSettlementsDueToMerchantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_61915c3c-a515-4e80-9de9-79b188ef7cc7" xlink:to="loc_prth_CardSettlementsDueToMerchantsMember_62e1f953-5e4f-45e7-9cef-bfb1f66e95e7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DueToACHPayeesMember_99bb73c3-3047-44bd-9bbe-f4facd141e31" xlink:href="prth-20200930.xsd#prth_DueToACHPayeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_61915c3c-a515-4e80-9de9-79b188ef7cc7" xlink:to="loc_prth_DueToACHPayeesMember_99bb73c3-3047-44bd-9bbe-f4facd141e31" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/GOODWILLANDOTHERINTANGIBLEASSETS" xlink:type="simple" xlink:href="prth-20200930.xsd#GOODWILLANDOTHERINTANGIBLEASSETS"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/GOODWILLANDOTHERINTANGIBLEASSETS" xlink:type="extended" id="ia41f549fc20c40589c9c8f6d2eed02c3_GOODWILLANDOTHERINTANGIBLEASSETS"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/GOODWILLANDOTHERINTANGIBLEASSETSTables" xlink:type="simple" xlink:href="prth-20200930.xsd#GOODWILLANDOTHERINTANGIBLEASSETSTables"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/GOODWILLANDOTHERINTANGIBLEASSETSTables" xlink:type="extended" id="i16603923deac47ae8847827c6ae4e4a7_GOODWILLANDOTHERINTANGIBLEASSETSTables"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/GOODWILLANDOTHERINTANGIBLEASSETSGoodwillAllocationDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#GOODWILLANDOTHERINTANGIBLEASSETSGoodwillAllocationDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/GOODWILLANDOTHERINTANGIBLEASSETSGoodwillAllocationDetails" xlink:type="extended" id="i5112906d5ac7475ca3d8c2e96e6d024d_GOODWILLANDOTHERINTANGIBLEASSETSGoodwillAllocationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_25ca38c9-dde2-42d1-b6e2-8c6fe03f3d8d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_6c59e0c2-a6eb-4ea3-829c-623e79e0dd39" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_25ca38c9-dde2-42d1-b6e2-8c6fe03f3d8d" xlink:to="loc_us-gaap_Goodwill_6c59e0c2-a6eb-4ea3-829c-623e79e0dd39" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_4f2ba801-13f0-45ae-8dae-a440b0afc467" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_25ca38c9-dde2-42d1-b6e2-8c6fe03f3d8d" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_4f2ba801-13f0-45ae-8dae-a440b0afc467" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_8d0368dc-fe03-4a69-a0cc-6868aa06e95b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_4f2ba801-13f0-45ae-8dae-a440b0afc467" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_8d0368dc-fe03-4a69-a0cc-6868aa06e95b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_8d0368dc-fe03-4a69-a0cc-6868aa06e95b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8d0368dc-fe03-4a69-a0cc-6868aa06e95b" xlink:to="loc_us-gaap_SegmentDomain_8d0368dc-fe03-4a69-a0cc-6868aa06e95b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_3311d3f8-5c7a-4682-b8f2-586722ed1902" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8d0368dc-fe03-4a69-a0cc-6868aa06e95b" xlink:to="loc_us-gaap_SegmentDomain_3311d3f8-5c7a-4682-b8f2-586722ed1902" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ConsumerPaymentsMember_58fb21b1-653d-40f1-b37a-72bef9d95c1c" xlink:href="prth-20200930.xsd#prth_ConsumerPaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_3311d3f8-5c7a-4682-b8f2-586722ed1902" xlink:to="loc_prth_ConsumerPaymentsMember_58fb21b1-653d-40f1-b37a-72bef9d95c1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_IntegratedPartnersMember_3e853af7-3676-48f6-b199-dbe6665aec2f" xlink:href="prth-20200930.xsd#prth_IntegratedPartnersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_3311d3f8-5c7a-4682-b8f2-586722ed1902" xlink:to="loc_prth_IntegratedPartnersMember_3e853af7-3676-48f6-b199-dbe6665aec2f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/GOODWILLANDOTHERINTANGIBLEASSETSNarrativeDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#GOODWILLANDOTHERINTANGIBLEASSETSNarrativeDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/GOODWILLANDOTHERINTANGIBLEASSETSNarrativeDetails" xlink:type="extended" id="i276c7250d82b4b3ab48b320ba3a48c88_GOODWILLANDOTHERINTANGIBLEASSETSNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0ff2cc78-90db-4fa1-a25d-573a4bd45a6e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_216c114e-b64f-4555-bedf-602dcd308185" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0ff2cc78-90db-4fa1-a25d-573a4bd45a6e" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_216c114e-b64f-4555-bedf-602dcd308185" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_9517c36e-70cd-4fb0-a0d6-15b46ff88a28" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0ff2cc78-90db-4fa1-a25d-573a4bd45a6e" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_9517c36e-70cd-4fb0-a0d6-15b46ff88a28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_16291496-476b-4f8d-8a24-67acef3a813f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0ff2cc78-90db-4fa1-a25d-573a4bd45a6e" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_16291496-476b-4f8d-8a24-67acef3a813f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_56866e02-fb45-4dbe-bd60-071ba1082581" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0ff2cc78-90db-4fa1-a25d-573a4bd45a6e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_56866e02-fb45-4dbe-bd60-071ba1082581" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsFairValueDisclosure_1399353d-6a67-4c5e-93c4-f53de16067e1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0ff2cc78-90db-4fa1-a25d-573a4bd45a6e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsFairValueDisclosure_1399353d-6a67-4c5e-93c4-f53de16067e1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_0e139d7e-8ea1-4bbf-9225-f914a1ee84d8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ImpairmentOfIntangibleAssetsFinitelived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0ff2cc78-90db-4fa1-a25d-573a4bd45a6e" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_0e139d7e-8ea1-4bbf-9225-f914a1ee84d8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_ad903b17-a1a2-4f1f-a1ac-fc79ae9c7634" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0ff2cc78-90db-4fa1-a25d-573a4bd45a6e" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_ad903b17-a1a2-4f1f-a1ac-fc79ae9c7634" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_06146a80-a1bc-4a77-8619-e24c3dc6b65e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_ad903b17-a1a2-4f1f-a1ac-fc79ae9c7634" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_06146a80-a1bc-4a77-8619-e24c3dc6b65e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_06146a80-a1bc-4a77-8619-e24c3dc6b65e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_06146a80-a1bc-4a77-8619-e24c3dc6b65e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_06146a80-a1bc-4a77-8619-e24c3dc6b65e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_47914f47-4ae5-466b-8c4b-81dcb4ffe9a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_06146a80-a1bc-4a77-8619-e24c3dc6b65e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_47914f47-4ae5-466b-8c4b-81dcb4ffe9a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ResidualBuyoutsMember_ceaa27c5-51cd-433e-ab9a-9020aff0b32a" xlink:href="prth-20200930.xsd#prth_ResidualBuyoutsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_47914f47-4ae5-466b-8c4b-81dcb4ffe9a0" xlink:to="loc_prth_ResidualBuyoutsMember_ceaa27c5-51cd-433e-ab9a-9020aff0b32a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_47291eb4-d1f4-4670-80d8-0a896530d935" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_ad903b17-a1a2-4f1f-a1ac-fc79ae9c7634" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_47291eb4-d1f4-4670-80d8-0a896530d935" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_47291eb4-d1f4-4670-80d8-0a896530d935_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_47291eb4-d1f4-4670-80d8-0a896530d935" xlink:to="loc_us-gaap_SegmentDomain_47291eb4-d1f4-4670-80d8-0a896530d935_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_9ec42adc-00c5-4040-bd33-fbc163472f09" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_47291eb4-d1f4-4670-80d8-0a896530d935" xlink:to="loc_us-gaap_SegmentDomain_9ec42adc-00c5-4040-bd33-fbc163472f09" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ConsumerPaymentsMember_60387a6f-8b36-46d9-a016-eae6b692a280" xlink:href="prth-20200930.xsd#prth_ConsumerPaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9ec42adc-00c5-4040-bd33-fbc163472f09" xlink:to="loc_prth_ConsumerPaymentsMember_60387a6f-8b36-46d9-a016-eae6b692a280" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/GOODWILLANDOTHERINTANGIBLEASSETSIntangibleAssetsDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#GOODWILLANDOTHERINTANGIBLEASSETSIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/GOODWILLANDOTHERINTANGIBLEASSETSIntangibleAssetsDetails" xlink:type="extended" id="i8870fb67096449f0a623b3bfa9544490_GOODWILLANDOTHERINTANGIBLEASSETSIntangibleAssetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_87e2fb6d-e27f-431b-bd92-b0cafd9c0b50" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_b9d59a58-362a-4be8-a56b-7d2ea6c3efed" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_87e2fb6d-e27f-431b-bd92-b0cafd9c0b50" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_b9d59a58-362a-4be8-a56b-7d2ea6c3efed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_473fca09-6886-4487-841d-9ee1d5b5615d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_87e2fb6d-e27f-431b-bd92-b0cafd9c0b50" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_473fca09-6886-4487-841d-9ee1d5b5615d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_FiniteLivedIntangibleAssetsAccumulatedImpairmentAllowance_05010a99-350e-44f0-9fa7-be0a4d8fa811" xlink:href="prth-20200930.xsd#prth_FiniteLivedIntangibleAssetsAccumulatedImpairmentAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_87e2fb6d-e27f-431b-bd92-b0cafd9c0b50" xlink:to="loc_prth_FiniteLivedIntangibleAssetsAccumulatedImpairmentAllowance_05010a99-350e-44f0-9fa7-be0a4d8fa811" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_1ef2657f-d441-4cdd-b58e-e9aad952ea15" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_87e2fb6d-e27f-431b-bd92-b0cafd9c0b50" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_1ef2657f-d441-4cdd-b58e-e9aad952ea15" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0ec3c673-8313-4249-8e59-5785fedfce37" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_87e2fb6d-e27f-431b-bd92-b0cafd9c0b50" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0ec3c673-8313-4249-8e59-5785fedfce37" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_53fd811c-6d41-43e5-b9a0-d9b595856273" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0ec3c673-8313-4249-8e59-5785fedfce37" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_53fd811c-6d41-43e5-b9a0-d9b595856273" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_53fd811c-6d41-43e5-b9a0-d9b595856273_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_53fd811c-6d41-43e5-b9a0-d9b595856273" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_53fd811c-6d41-43e5-b9a0-d9b595856273_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a4feac6c-0918-432f-9bd6-5090a031b537" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_53fd811c-6d41-43e5-b9a0-d9b595856273" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a4feac6c-0918-432f-9bd6-5090a031b537" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceAgreementsMember_6861d2f8-5bc2-449c-81ec-a19d7ca5d095" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ServiceAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a4feac6c-0918-432f-9bd6-5090a031b537" xlink:to="loc_us-gaap_ServiceAgreementsMember_6861d2f8-5bc2-449c-81ec-a19d7ca5d095" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_1b4f4fef-3be7-4656-8d3f-87d58c646dc0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a4feac6c-0918-432f-9bd6-5090a031b537" xlink:to="loc_us-gaap_CustomerRelationshipsMember_1b4f4fef-3be7-4656-8d3f-87d58c646dc0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ResidualBuyoutsMember_8991d535-5d70-4cf7-a03d-2c010336d3c0" xlink:href="prth-20200930.xsd#prth_ResidualBuyoutsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a4feac6c-0918-432f-9bd6-5090a031b537" xlink:to="loc_prth_ResidualBuyoutsMember_8991d535-5d70-4cf7-a03d-2c010336d3c0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_4ee10181-610d-44ac-920c-3b7bbe33f322" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncompeteAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a4feac6c-0918-432f-9bd6-5090a031b537" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_4ee10181-610d-44ac-920c-3b7bbe33f322" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_2e73abb9-d417-4c3f-a496-3d8941500c82" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a4feac6c-0918-432f-9bd6-5090a031b537" xlink:to="loc_us-gaap_TradeNamesMember_2e73abb9-d417-4c3f-a496-3d8941500c82" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_62b61557-f5e3-4657-8dd5-0542c470dbd6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a4feac6c-0918-432f-9bd6-5090a031b537" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_62b61557-f5e3-4657-8dd5-0542c470dbd6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ISORelationshipsMember_775309cf-4be4-4f17-8746-e1528160c042" xlink:href="prth-20200930.xsd#prth_ISORelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a4feac6c-0918-432f-9bd6-5090a031b537" xlink:to="loc_prth_ISORelationshipsMember_775309cf-4be4-4f17-8746-e1528160c042" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/PROPERTYEQUIPMENTANDSOFTWARE" xlink:type="simple" xlink:href="prth-20200930.xsd#PROPERTYEQUIPMENTANDSOFTWARE"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/PROPERTYEQUIPMENTANDSOFTWARE" xlink:type="extended" id="i809ff89e0ffe422b9271bbbdfbcd1ff9_PROPERTYEQUIPMENTANDSOFTWARE"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/PROPERTYEQUIPMENTANDSOFTWARETables" xlink:type="simple" xlink:href="prth-20200930.xsd#PROPERTYEQUIPMENTANDSOFTWARETables"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/PROPERTYEQUIPMENTANDSOFTWARETables" xlink:type="extended" id="i5e2e57f09429484eb52e086fa0766684_PROPERTYEQUIPMENTANDSOFTWARETables"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/PROPERTYEQUIPMENTANDSOFTWARENarrativeandScheduleofPropertyEquipmentandSoftwareDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#PROPERTYEQUIPMENTANDSOFTWARENarrativeandScheduleofPropertyEquipmentandSoftwareDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/PROPERTYEQUIPMENTANDSOFTWARENarrativeandScheduleofPropertyEquipmentandSoftwareDetails" xlink:type="extended" id="i2e04254c5aad44bb80372aa8ac33f4d8_PROPERTYEQUIPMENTANDSOFTWARENarrativeandScheduleofPropertyEquipmentandSoftwareDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4b38902c-aea1-430f-9681-2817cf2c8ee3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_87af106b-2ed8-452f-82e6-349eaadb98ba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4b38902c-aea1-430f-9681-2817cf2c8ee3" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_87af106b-2ed8-452f-82e6-349eaadb98ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_6676cea9-73bf-4d43-80c7-fcf9628bab60" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4b38902c-aea1-430f-9681-2817cf2c8ee3" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_6676cea9-73bf-4d43-80c7-fcf9628bab60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_8e63e72a-d257-46a0-ba4b-9565f229597e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4b38902c-aea1-430f-9681-2817cf2c8ee3" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_8e63e72a-d257-46a0-ba4b-9565f229597e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_742376b3-e22b-4c28-abf5-101beb942c12" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4b38902c-aea1-430f-9681-2817cf2c8ee3" xlink:to="loc_us-gaap_Depreciation_742376b3-e22b-4c28-abf5-101beb942c12" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_87604c3a-d255-4644-a91e-5463e683b45f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4b38902c-aea1-430f-9681-2817cf2c8ee3" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_87604c3a-d255-4644-a91e-5463e683b45f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2ca02647-d9ea-4ca6-8b81-4eca448816b8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_87604c3a-d255-4644-a91e-5463e683b45f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2ca02647-d9ea-4ca6-8b81-4eca448816b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2ca02647-d9ea-4ca6-8b81-4eca448816b8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2ca02647-d9ea-4ca6-8b81-4eca448816b8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2ca02647-d9ea-4ca6-8b81-4eca448816b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_96856557-5ea3-4dee-acfa-e43266d0428e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2ca02647-d9ea-4ca6-8b81-4eca448816b8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_96856557-5ea3-4dee-acfa-e43266d0428e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_dd4adcb2-b693-4037-82de-49ec80eebbce" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_96856557-5ea3-4dee-acfa-e43266d0428e" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_dd4adcb2-b693-4037-82de-49ec80eebbce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquipmentMember_7d46a006-3ac4-4361-8016-07309cf4afe9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_96856557-5ea3-4dee-acfa-e43266d0428e" xlink:to="loc_us-gaap_EquipmentMember_7d46a006-3ac4-4361-8016-07309cf4afe9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_23d51f7b-e125-440b-a08e-4903cc0368be" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_96856557-5ea3-4dee-acfa-e43266d0428e" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_23d51f7b-e125-440b-a08e-4903cc0368be" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_692c6bf7-33e1-4698-9f5e-8b63677b27d8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_96856557-5ea3-4dee-acfa-e43266d0428e" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_692c6bf7-33e1-4698-9f5e-8b63677b27d8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_89fd916c-8f45-47e2-af56-939b8a441ef5" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_87604c3a-d255-4644-a91e-5463e683b45f" xlink:to="loc_srt_RangeAxis_89fd916c-8f45-47e2-af56-939b8a441ef5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_89fd916c-8f45-47e2-af56-939b8a441ef5_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_89fd916c-8f45-47e2-af56-939b8a441ef5" xlink:to="loc_srt_RangeMember_89fd916c-8f45-47e2-af56-939b8a441ef5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_9da6f601-536c-4980-8f47-6786d14cf3cb" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_89fd916c-8f45-47e2-af56-939b8a441ef5" xlink:to="loc_srt_RangeMember_9da6f601-536c-4980-8f47-6786d14cf3cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_28b3798c-81b9-4b65-bd63-7ee02f7c2abc" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_9da6f601-536c-4980-8f47-6786d14cf3cb" xlink:to="loc_srt_MinimumMember_28b3798c-81b9-4b65-bd63-7ee02f7c2abc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_79057fc7-5d61-4d35-ab93-35f44ca9d46d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_9da6f601-536c-4980-8f47-6786d14cf3cb" xlink:to="loc_srt_MaximumMember_79057fc7-5d61-4d35-ab93-35f44ca9d46d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/ACCOUNTSPAYABLEANDACCRUEDEXPENSES" xlink:type="simple" xlink:href="prth-20200930.xsd#ACCOUNTSPAYABLEANDACCRUEDEXPENSES"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/ACCOUNTSPAYABLEANDACCRUEDEXPENSES" xlink:type="extended" id="i1d8e9acb25b245988e33a78d0dcd6c88_ACCOUNTSPAYABLEANDACCRUEDEXPENSES"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/ACCOUNTSPAYABLEANDACCRUEDEXPENSESTables" xlink:type="simple" xlink:href="prth-20200930.xsd#ACCOUNTSPAYABLEANDACCRUEDEXPENSESTables"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/ACCOUNTSPAYABLEANDACCRUEDEXPENSESTables" xlink:type="extended" id="idee7a3b9cc2d40559b032751e2113ce1_ACCOUNTSPAYABLEANDACCRUEDEXPENSESTables"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/ACCOUNTSPAYABLEANDACCRUEDEXPENSESScheduleofAccountsPayableandAccruedExpensesDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#ACCOUNTSPAYABLEANDACCRUEDEXPENSESScheduleofAccountsPayableandAccruedExpensesDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/ACCOUNTSPAYABLEANDACCRUEDEXPENSESScheduleofAccountsPayableandAccruedExpensesDetails" xlink:type="extended" id="i1b9eda3fa31d4ad09a58d89c6f0db241_ACCOUNTSPAYABLEANDACCRUEDEXPENSESScheduleofAccountsPayableandAccruedExpensesDetails"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/DEBTOBLIGATIONS" xlink:type="simple" xlink:href="prth-20200930.xsd#DEBTOBLIGATIONS"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/DEBTOBLIGATIONS" xlink:type="extended" id="i8a84abb836bd44069c257bc610a2e334_DEBTOBLIGATIONS"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/DEBTOBLIGATIONSTables" xlink:type="simple" xlink:href="prth-20200930.xsd#DEBTOBLIGATIONSTables"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/DEBTOBLIGATIONSTables" xlink:type="extended" id="iad4bcd30fb4644279ddb89cda8dddb43_DEBTOBLIGATIONSTables"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/DEBTOBLIGATIONSScheduleofLongTermDebtDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#DEBTOBLIGATIONSScheduleofLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/DEBTOBLIGATIONSScheduleofLongTermDebtDetails" xlink:type="extended" id="id7bc361465834ffca7fb48cea9d9334a_DEBTOBLIGATIONSScheduleofLongTermDebtDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_2ebd6214-7cbd-403f-8403-62c695e62a0d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_b70d28ff-b746-4df3-84fd-bfebc78d158a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2ebd6214-7cbd-403f-8403-62c695e62a0d" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_b70d28ff-b746-4df3-84fd-bfebc78d158a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_9b8c2fe6-7769-4c78-a032-cfd118ad8df2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2ebd6214-7cbd-403f-8403-62c695e62a0d" xlink:to="loc_us-gaap_LongTermDebtCurrent_9b8c2fe6-7769-4c78-a032-cfd118ad8df2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_b11ae107-c800-43b1-8b52-9619c73c8186" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2ebd6214-7cbd-403f-8403-62c695e62a0d" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_b11ae107-c800-43b1-8b52-9619c73c8186" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_fdcfab1c-6ff6-409b-a36a-6c72761e151a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2ebd6214-7cbd-403f-8403-62c695e62a0d" xlink:to="loc_us-gaap_LongTermDebt_fdcfab1c-6ff6-409b-a36a-6c72761e151a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_91f62096-c10f-47fb-814a-1925c39a11d5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2ebd6214-7cbd-403f-8403-62c695e62a0d" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_91f62096-c10f-47fb-814a-1925c39a11d5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_17346db3-a388-4d7c-9d37-67b2ed9e46ae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2ebd6214-7cbd-403f-8403-62c695e62a0d" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_17346db3-a388-4d7c-9d37-67b2ed9e46ae" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DebtInstrumentInterestRateLIBORFloor_25cda6a0-8297-4d6c-88a3-98711ae09637" xlink:href="prth-20200930.xsd#prth_DebtInstrumentInterestRateLIBORFloor"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2ebd6214-7cbd-403f-8403-62c695e62a0d" xlink:to="loc_prth_DebtInstrumentInterestRateLIBORFloor_25cda6a0-8297-4d6c-88a3-98711ae09637" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_5ebc7dee-2c5c-4812-8852-8c2299709bb6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2ebd6214-7cbd-403f-8403-62c695e62a0d" xlink:to="loc_us-gaap_DebtInstrumentTable_5ebc7dee-2c5c-4812-8852-8c2299709bb6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_d7a2f752-ddf4-4b31-b06e-535ff14a3854" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5ebc7dee-2c5c-4812-8852-8c2299709bb6" xlink:to="loc_us-gaap_DebtInstrumentAxis_d7a2f752-ddf4-4b31-b06e-535ff14a3854" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_d7a2f752-ddf4-4b31-b06e-535ff14a3854_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_d7a2f752-ddf4-4b31-b06e-535ff14a3854" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_d7a2f752-ddf4-4b31-b06e-535ff14a3854_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_54f53fed-1266-484e-9745-d84112f026e8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_d7a2f752-ddf4-4b31-b06e-535ff14a3854" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_54f53fed-1266-484e-9745-d84112f026e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_SeniorTermLoanMaturingJanuary32023Member_e95fd774-3e50-41b3-93c8-0f420e3d50d4" xlink:href="prth-20200930.xsd#prth_SeniorTermLoanMaturingJanuary32023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_54f53fed-1266-484e-9745-d84112f026e8" xlink:to="loc_prth_SeniorTermLoanMaturingJanuary32023Member_e95fd774-3e50-41b3-93c8-0f420e3d50d4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_SubordinatedTermLoanMaturingJuly32023Member_62758f36-8579-42b6-9ea7-2596e29af926" xlink:href="prth-20200930.xsd#prth_SubordinatedTermLoanMaturingJuly32023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_54f53fed-1266-484e-9745-d84112f026e8" xlink:to="loc_prth_SubordinatedTermLoanMaturingJuly32023Member_62758f36-8579-42b6-9ea7-2596e29af926" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_9bc49c15-d99d-4354-868c-0cbd408fd113" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5ebc7dee-2c5c-4812-8852-8c2299709bb6" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_9bc49c15-d99d-4354-868c-0cbd408fd113" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_9bc49c15-d99d-4354-868c-0cbd408fd113_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_9bc49c15-d99d-4354-868c-0cbd408fd113" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_9bc49c15-d99d-4354-868c-0cbd408fd113_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_bf526d55-902c-456d-afac-0bad1a4fc441" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_9bc49c15-d99d-4354-868c-0cbd408fd113" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_bf526d55-902c-456d-afac-0bad1a4fc441" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_SyndicateOfLendersMember_9c902553-6d11-4457-9dab-cb49df2cbf12" xlink:href="prth-20200930.xsd#prth_SyndicateOfLendersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_bf526d55-902c-456d-afac-0bad1a4fc441" xlink:to="loc_prth_SyndicateOfLendersMember_9c902553-6d11-4457-9dab-cb49df2cbf12" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_GoldmanSachsSpecialtyLendingGroupMember_7fab34e4-8a93-4cd3-96e0-f7540fa87967" xlink:href="prth-20200930.xsd#prth_GoldmanSachsSpecialtyLendingGroupMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_bf526d55-902c-456d-afac-0bad1a4fc441" xlink:to="loc_prth_GoldmanSachsSpecialtyLendingGroupMember_7fab34e4-8a93-4cd3-96e0-f7540fa87967" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_a32c5e3f-250e-48d6-a4ca-bc201b612c0e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5ebc7dee-2c5c-4812-8852-8c2299709bb6" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_a32c5e3f-250e-48d6-a4ca-bc201b612c0e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_a32c5e3f-250e-48d6-a4ca-bc201b612c0e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_a32c5e3f-250e-48d6-a4ca-bc201b612c0e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_a32c5e3f-250e-48d6-a4ca-bc201b612c0e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_324deaab-9abb-4c02-9bab-7a25a55627b4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_a32c5e3f-250e-48d6-a4ca-bc201b612c0e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_324deaab-9abb-4c02-9bab-7a25a55627b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_89fbc9dd-8a67-4303-8f88-f65774eae52a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_324deaab-9abb-4c02-9bab-7a25a55627b4" xlink:to="loc_us-gaap_SeniorNotesMember_89fbc9dd-8a67-4303-8f88-f65774eae52a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_8ab7fb8b-0368-4375-9a34-d3460650f873" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_324deaab-9abb-4c02-9bab-7a25a55627b4" xlink:to="loc_us-gaap_LineOfCreditMember_8ab7fb8b-0368-4375-9a34-d3460650f873" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedDebtMember_2c919cd1-61d5-4a14-bc05-d94ed8978845" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubordinatedDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_324deaab-9abb-4c02-9bab-7a25a55627b4" xlink:to="loc_us-gaap_SubordinatedDebtMember_2c919cd1-61d5-4a14-bc05-d94ed8978845" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_cfe21797-96c6-44f0-a467-bb0d4f2a423b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5ebc7dee-2c5c-4812-8852-8c2299709bb6" xlink:to="loc_us-gaap_CreditFacilityAxis_cfe21797-96c6-44f0-a467-bb0d4f2a423b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_cfe21797-96c6-44f0-a467-bb0d4f2a423b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_cfe21797-96c6-44f0-a467-bb0d4f2a423b" xlink:to="loc_us-gaap_CreditFacilityDomain_cfe21797-96c6-44f0-a467-bb0d4f2a423b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_f6b7e460-7108-4e6f-bdb9-5ce37202645c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_cfe21797-96c6-44f0-a467-bb0d4f2a423b" xlink:to="loc_us-gaap_CreditFacilityDomain_f6b7e460-7108-4e6f-bdb9-5ce37202645c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_6de77ec4-4bca-4afa-b145-9d1e14b3f151" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_f6b7e460-7108-4e6f-bdb9-5ce37202645c" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_6de77ec4-4bca-4afa-b145-9d1e14b3f151" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_94626338-8568-48ac-8b57-59aa577fcca9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_f6b7e460-7108-4e6f-bdb9-5ce37202645c" xlink:to="loc_us-gaap_LetterOfCreditMember_94626338-8568-48ac-8b57-59aa577fcca9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_f62a1665-9ea1-4178-8d8e-ae4a81beea25" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5ebc7dee-2c5c-4812-8852-8c2299709bb6" xlink:to="loc_us-gaap_VariableRateAxis_f62a1665-9ea1-4178-8d8e-ae4a81beea25" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_f62a1665-9ea1-4178-8d8e-ae4a81beea25_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_f62a1665-9ea1-4178-8d8e-ae4a81beea25" xlink:to="loc_us-gaap_VariableRateDomain_f62a1665-9ea1-4178-8d8e-ae4a81beea25_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_d5e5c039-9308-48f6-9a96-44adf296dd6c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_f62a1665-9ea1-4178-8d8e-ae4a81beea25" xlink:to="loc_us-gaap_VariableRateDomain_d5e5c039-9308-48f6-9a96-44adf296dd6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_ffa5bcab-8b19-4cf6-ad75-4a0b6241d77d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_d5e5c039-9308-48f6-9a96-44adf296dd6c" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_ffa5bcab-8b19-4cf6-ad75-4a0b6241d77d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PaymentInKindInterestRateMember_7cac28ca-65f7-4483-b2d0-b90cab14c6a9" xlink:href="prth-20200930.xsd#prth_PaymentInKindInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_d5e5c039-9308-48f6-9a96-44adf296dd6c" xlink:to="loc_prth_PaymentInKindInterestRateMember_7cac28ca-65f7-4483-b2d0-b90cab14c6a9" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/DEBTOBLIGATIONSNarrativeDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#DEBTOBLIGATIONSNarrativeDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/DEBTOBLIGATIONSNarrativeDetails" xlink:type="extended" id="i840256ffeae848e8b131b2d27e6583e8_DEBTOBLIGATIONSNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_2f4ff9a7-5a46-4376-a5ec-f7f83e850987" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_2f4ff9a7-5a46-4376-a5ec-f7f83e850987" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_9fe43c5c-1249-47e1-85f7-cc198259d764" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_9fe43c5c-1249-47e1-85f7-cc198259d764" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DebtInstrumentInterestRateLIBORFloor_57e741ae-abed-4496-b3e0-21b6e164440d" xlink:href="prth-20200930.xsd#prth_DebtInstrumentInterestRateLIBORFloor"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_prth_DebtInstrumentInterestRateLIBORFloor_57e741ae-abed-4496-b3e0-21b6e164440d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_a8584fd9-9abd-4b6e-ade3-554304364125" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_a8584fd9-9abd-4b6e-ade3-554304364125" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_f3802692-5995-44f5-8b07-e93331999f99" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_f3802692-5995-44f5-8b07-e93331999f99" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_30494d42-c9b3-40a7-8e09-4a74e37ef971" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_30494d42-c9b3-40a7-8e09-4a74e37ef971" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateIncreaseDecrease_4eb704bc-07a1-4b32-b6cc-07a7f96c413a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_DebtInstrumentInterestRateIncreaseDecrease_4eb704bc-07a1-4b32-b6cc-07a7f96c413a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_f1034714-9cfc-4920-9cee-2a98edf03b22" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_f1034714-9cfc-4920-9cee-2a98edf03b22" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PaymentForDebtExtinguishmentOrDebtPrepaymentCostPrincipalOnly_486371e8-7e49-4e09-ae94-3000ff2d21f8" xlink:href="prth-20200930.xsd#prth_PaymentForDebtExtinguishmentOrDebtPrepaymentCostPrincipalOnly"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_prth_PaymentForDebtExtinguishmentOrDebtPrepaymentCostPrincipalOnly_486371e8-7e49-4e09-ae94-3000ff2d21f8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PaymentForDebtExtinguishmentOrDebtPrepaymentCostAdditionalPrincipal_029d37c4-5de5-4d50-a0dd-998439388d3f" xlink:href="prth-20200930.xsd#prth_PaymentForDebtExtinguishmentOrDebtPrepaymentCostAdditionalPrincipal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_prth_PaymentForDebtExtinguishmentOrDebtPrepaymentCostAdditionalPrincipal_029d37c4-5de5-4d50-a0dd-998439388d3f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_81f37888-54cf-4b8a-b1c0-5c3e611bc043" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_81f37888-54cf-4b8a-b1c0-5c3e611bc043" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_LineOfCreditFaciityPenaltyPercentageOnDefaultPrincipalPrepayments_71983869-8e30-4f47-9fa7-84eba0deedf8" xlink:href="prth-20200930.xsd#prth_LineOfCreditFaciityPenaltyPercentageOnDefaultPrincipalPrepayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_prth_LineOfCreditFaciityPenaltyPercentageOnDefaultPrincipalPrepayments_71983869-8e30-4f47-9fa7-84eba0deedf8" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_d778db2c-840e-4be3-94ff-8bd6563fbff1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_LineOfCredit_d778db2c-840e-4be3-94ff-8bd6563fbff1" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrentAndNoncurrent_8029586e-248a-48e5-9257-25f563181252" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestPayableCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_InterestPayableCurrentAndNoncurrent_8029586e-248a-48e5-9257-25f563181252" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaidInKindInterest_bece2c19-12d0-4f91-903f-f7e30327c437" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaidInKindInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_PaidInKindInterest_bece2c19-12d0-4f91-903f-f7e30327c437" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_45cd5294-e2d7-4a0b-8ede-9e391d45bd3c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_InterestExpense_45cd5294-e2d7-4a0b-8ede-9e391d45bd3c" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeeAmount_fc89d435-c8ec-4305-9f80-5a0383232bf6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeeAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeeAmount_fc89d435-c8ec-4305-9f80-5a0383232bf6" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_CapitalizedLenderFees_ea87e64c-74b1-47fa-b0f8-120b014b65e9" xlink:href="prth-20200930.xsd#prth_CapitalizedLenderFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_prth_CapitalizedLenderFees_ea87e64c-74b1-47fa-b0f8-120b014b65e9" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DebtInstrumentUnamortizedDiscountIncludingCapitalizedFees.NetOfAmortizationExpense_6b3ee488-54a0-4e08-9a3f-993f7d4a4e95" xlink:href="prth-20200930.xsd#prth_DebtInstrumentUnamortizedDiscountIncludingCapitalizedFees.NetOfAmortizationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_prth_DebtInstrumentUnamortizedDiscountIncludingCapitalizedFees.NetOfAmortizationExpense_6b3ee488-54a0-4e08-9a3f-993f7d4a4e95" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_AmortizationOfDebtDiscountPremiumAndDebtIssuanceCosts_d12668e2-48a8-437a-be65-c31450d8c4c6" xlink:href="prth-20200930.xsd#prth_AmortizationOfDebtDiscountPremiumAndDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_prth_AmortizationOfDebtDiscountPremiumAndDebtIssuanceCosts_d12668e2-48a8-437a-be65-c31450d8c4c6" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DebtPrepaymentCostUnamortizedLoanCostsAndDiscountExpensed_12f15f2c-421b-4362-8480-e0d76bf5bad8" xlink:href="prth-20200930.xsd#prth_DebtPrepaymentCostUnamortizedLoanCostsAndDiscountExpensed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_prth_DebtPrepaymentCostUnamortizedLoanCostsAndDiscountExpensed_12f15f2c-421b-4362-8480-e0d76bf5bad8" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_aa5dc260-ebd6-4af1-8722-adcf7bef402b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_aa5dc260-ebd6-4af1-8722-adcf7bef402b" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DebtCovenantMaximumNetLeverageRatio_5a76a427-48a0-45a7-957f-972b61f2f157" xlink:href="prth-20200930.xsd#prth_DebtCovenantMaximumNetLeverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_prth_DebtCovenantMaximumNetLeverageRatio_5a76a427-48a0-45a7-957f-972b61f2f157" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_ad369d2b-1efd-4dd9-83c5-ed1f71626cce" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_84b2dd48-340b-4aa7-a9fd-61fd06644ac9" xlink:to="loc_us-gaap_DebtInstrumentTable_ad369d2b-1efd-4dd9-83c5-ed1f71626cce" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_9f854d3e-8d99-4891-9cc1-8ea21c95e5bc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_ad369d2b-1efd-4dd9-83c5-ed1f71626cce" xlink:to="loc_us-gaap_VariableRateAxis_9f854d3e-8d99-4891-9cc1-8ea21c95e5bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_9f854d3e-8d99-4891-9cc1-8ea21c95e5bc_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_9f854d3e-8d99-4891-9cc1-8ea21c95e5bc" xlink:to="loc_us-gaap_VariableRateDomain_9f854d3e-8d99-4891-9cc1-8ea21c95e5bc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_e5968f95-c49e-4ff7-8fc4-711508746d06" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_9f854d3e-8d99-4891-9cc1-8ea21c95e5bc" xlink:to="loc_us-gaap_VariableRateDomain_e5968f95-c49e-4ff7-8fc4-711508746d06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ApplicableMarginMember_255f4954-7c21-460a-a4c8-a53f1cee632e" xlink:href="prth-20200930.xsd#prth_ApplicableMarginMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_e5968f95-c49e-4ff7-8fc4-711508746d06" xlink:to="loc_prth_ApplicableMarginMember_255f4954-7c21-460a-a4c8-a53f1cee632e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_e6fa6b39-6c91-42c8-bf63-a3833034bc70" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_ad369d2b-1efd-4dd9-83c5-ed1f71626cce" xlink:to="loc_srt_RangeAxis_e6fa6b39-6c91-42c8-bf63-a3833034bc70" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e6fa6b39-6c91-42c8-bf63-a3833034bc70_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_e6fa6b39-6c91-42c8-bf63-a3833034bc70" xlink:to="loc_srt_RangeMember_e6fa6b39-6c91-42c8-bf63-a3833034bc70_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7670bafb-b8db-40c0-82e7-aac92ac8dd0c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_e6fa6b39-6c91-42c8-bf63-a3833034bc70" xlink:to="loc_srt_RangeMember_7670bafb-b8db-40c0-82e7-aac92ac8dd0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_91d79d2f-522f-4d8c-bdf5-a1fd1f8d030b" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7670bafb-b8db-40c0-82e7-aac92ac8dd0c" xlink:to="loc_srt_MinimumMember_91d79d2f-522f-4d8c-bdf5-a1fd1f8d030b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_26b958e2-8114-4c6a-8e82-882f342d4e82" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7670bafb-b8db-40c0-82e7-aac92ac8dd0c" xlink:to="loc_srt_MaximumMember_26b958e2-8114-4c6a-8e82-882f342d4e82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_823679fd-2583-497e-b5a0-c2f98845276d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_ad369d2b-1efd-4dd9-83c5-ed1f71626cce" xlink:to="loc_srt_StatementScenarioAxis_823679fd-2583-497e-b5a0-c2f98845276d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_823679fd-2583-497e-b5a0-c2f98845276d_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_823679fd-2583-497e-b5a0-c2f98845276d" xlink:to="loc_srt_ScenarioUnspecifiedDomain_823679fd-2583-497e-b5a0-c2f98845276d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_9e5d4417-b243-4694-8074-4c9025148465" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_823679fd-2583-497e-b5a0-c2f98845276d" xlink:to="loc_srt_ScenarioUnspecifiedDomain_9e5d4417-b243-4694-8074-4c9025148465" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_168db10d-9509-4094-b415-9b4613705acb" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_9e5d4417-b243-4694-8074-4c9025148465" xlink:to="loc_srt_ScenarioForecastMember_168db10d-9509-4094-b415-9b4613705acb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_aaa6f67c-ff53-4a8a-a178-59145324468b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_ad369d2b-1efd-4dd9-83c5-ed1f71626cce" xlink:to="loc_us-gaap_DebtInstrumentAxis_aaa6f67c-ff53-4a8a-a178-59145324468b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_aaa6f67c-ff53-4a8a-a178-59145324468b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_aaa6f67c-ff53-4a8a-a178-59145324468b" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_aaa6f67c-ff53-4a8a-a178-59145324468b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_9135d921-07d7-4754-8230-f4d90a3c7186" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_aaa6f67c-ff53-4a8a-a178-59145324468b" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_9135d921-07d7-4754-8230-f4d90a3c7186" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DelayedDrawMember_00376c49-66ab-4e2a-a307-66baaa356147" xlink:href="prth-20200930.xsd#prth_DelayedDrawMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_9135d921-07d7-4754-8230-f4d90a3c7186" xlink:to="loc_prth_DelayedDrawMember_00376c49-66ab-4e2a-a307-66baaa356147" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_SeniorTermLoanMaturingJanuary32023Member_65b99fa0-ea20-4f52-a6ab-a9156ba3ad7d" xlink:href="prth-20200930.xsd#prth_SeniorTermLoanMaturingJanuary32023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_9135d921-07d7-4754-8230-f4d90a3c7186" xlink:to="loc_prth_SeniorTermLoanMaturingJanuary32023Member_65b99fa0-ea20-4f52-a6ab-a9156ba3ad7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_a3fdbc1e-ab16-4768-b0a4-9d1223773942" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_ad369d2b-1efd-4dd9-83c5-ed1f71626cce" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_a3fdbc1e-ab16-4768-b0a4-9d1223773942" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_a3fdbc1e-ab16-4768-b0a4-9d1223773942_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_a3fdbc1e-ab16-4768-b0a4-9d1223773942" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_a3fdbc1e-ab16-4768-b0a4-9d1223773942_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_0a8ee4c6-907d-48b3-9da3-c3ce46b21a71" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_a3fdbc1e-ab16-4768-b0a4-9d1223773942" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_0a8ee4c6-907d-48b3-9da3-c3ce46b21a71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_GoldmanSachsSpecialtyLendingGroupMember_6de11c68-5f19-4429-b8d7-8a5520664451" xlink:href="prth-20200930.xsd#prth_GoldmanSachsSpecialtyLendingGroupMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_0a8ee4c6-907d-48b3-9da3-c3ce46b21a71" xlink:to="loc_prth_GoldmanSachsSpecialtyLendingGroupMember_6de11c68-5f19-4429-b8d7-8a5520664451" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_SyndicateOfLendersMember_0d240f45-89d5-4ff7-b236-c413f394b126" xlink:href="prth-20200930.xsd#prth_SyndicateOfLendersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_0a8ee4c6-907d-48b3-9da3-c3ce46b21a71" xlink:to="loc_prth_SyndicateOfLendersMember_0d240f45-89d5-4ff7-b236-c413f394b126" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_adee195a-f5fd-41af-9788-0790e6f13f4e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_ad369d2b-1efd-4dd9-83c5-ed1f71626cce" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_adee195a-f5fd-41af-9788-0790e6f13f4e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_adee195a-f5fd-41af-9788-0790e6f13f4e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_adee195a-f5fd-41af-9788-0790e6f13f4e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_adee195a-f5fd-41af-9788-0790e6f13f4e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_46ec2865-614b-43ed-be5d-ba14bff2cacc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_adee195a-f5fd-41af-9788-0790e6f13f4e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_46ec2865-614b-43ed-be5d-ba14bff2cacc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_b8f0121b-eb68-4f12-990c-c2c7c1deda0c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_46ec2865-614b-43ed-be5d-ba14bff2cacc" xlink:to="loc_us-gaap_LineOfCreditMember_b8f0121b-eb68-4f12-990c-c2c7c1deda0c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_090e7508-44b5-4f15-b8c6-bafedc07b06c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_46ec2865-614b-43ed-be5d-ba14bff2cacc" xlink:to="loc_us-gaap_LetterOfCreditMember_090e7508-44b5-4f15-b8c6-bafedc07b06c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_a0e7e20a-2234-44cf-9527-0519e02d30bf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_ad369d2b-1efd-4dd9-83c5-ed1f71626cce" xlink:to="loc_us-gaap_CreditFacilityAxis_a0e7e20a-2234-44cf-9527-0519e02d30bf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_a0e7e20a-2234-44cf-9527-0519e02d30bf_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_a0e7e20a-2234-44cf-9527-0519e02d30bf" xlink:to="loc_us-gaap_CreditFacilityDomain_a0e7e20a-2234-44cf-9527-0519e02d30bf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_52288c6d-0886-4c4a-9812-8b50f2eab70c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_a0e7e20a-2234-44cf-9527-0519e02d30bf" xlink:to="loc_us-gaap_CreditFacilityDomain_52288c6d-0886-4c4a-9812-8b50f2eab70c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_47df920e-0d1d-4aa4-8796-dbcc700273ea" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_52288c6d-0886-4c4a-9812-8b50f2eab70c" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_47df920e-0d1d-4aa4-8796-dbcc700273ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_SwingLineFacilityMember_063dc57e-3bf7-41d0-946b-4d3093d10e2b" xlink:href="prth-20200930.xsd#prth_SwingLineFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_52288c6d-0886-4c4a-9812-8b50f2eab70c" xlink:to="loc_prth_SwingLineFacilityMember_063dc57e-3bf7-41d0-946b-4d3093d10e2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_TermLoanMember_7214dfd1-ea47-40c0-bd10-50b92d98a0a0" xlink:href="prth-20200930.xsd#prth_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_52288c6d-0886-4c4a-9812-8b50f2eab70c" xlink:to="loc_prth_TermLoanMember_7214dfd1-ea47-40c0-bd10-50b92d98a0a0" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/DEBTOBLIGATIONSRollingMaturitiesofLongTermDebtDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#DEBTOBLIGATIONSRollingMaturitiesofLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/DEBTOBLIGATIONSRollingMaturitiesofLongTermDebtDetails" xlink:type="extended" id="ib9a091522c2740a7a1555c39f194dcaf_DEBTOBLIGATIONSRollingMaturitiesofLongTermDebtDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_87ce1ed3-be80-41a0-beb8-b2eb1168d4ad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextRollingTwelveMonths_e919ab19-064b-4c5e-8b0f-c9afe9e6b766" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextRollingTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_87ce1ed3-be80-41a0-beb8-b2eb1168d4ad" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextRollingTwelveMonths_e919ab19-064b-4c5e-8b0f-c9afe9e6b766" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearTwo_cc221466-0079-4501-9f4c-060e3dbaffc1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_87ce1ed3-be80-41a0-beb8-b2eb1168d4ad" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearTwo_cc221466-0079-4501-9f4c-060e3dbaffc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearThree_12b55819-a7be-4c52-ad84-2318ad86a837" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_87ce1ed3-be80-41a0-beb8-b2eb1168d4ad" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearThree_12b55819-a7be-4c52-ad84-2318ad86a837" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearFour_1aa8a434-db8a-4b13-8c82-29ec2ed660e2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_87ce1ed3-be80-41a0-beb8-b2eb1168d4ad" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearFour_1aa8a434-db8a-4b13-8c82-29ec2ed660e2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_87820a68-c814-43c3-a540-2af0f98ed3c2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_87ce1ed3-be80-41a0-beb8-b2eb1168d4ad" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_87820a68-c814-43c3-a540-2af0f98ed3c2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_d63c1b42-07a1-4f9d-8d4e-e09a010f0db7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_87ce1ed3-be80-41a0-beb8-b2eb1168d4ad" xlink:to="loc_us-gaap_DebtInstrumentTable_d63c1b42-07a1-4f9d-8d4e-e09a010f0db7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_adc3dfa5-2dc6-4fed-a758-2ab85cf77c27" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d63c1b42-07a1-4f9d-8d4e-e09a010f0db7" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_adc3dfa5-2dc6-4fed-a758-2ab85cf77c27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_adc3dfa5-2dc6-4fed-a758-2ab85cf77c27_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_adc3dfa5-2dc6-4fed-a758-2ab85cf77c27" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_adc3dfa5-2dc6-4fed-a758-2ab85cf77c27_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_98e9bf54-9467-467d-82c1-c44fe5fac7ca" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_adc3dfa5-2dc6-4fed-a758-2ab85cf77c27" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_98e9bf54-9467-467d-82c1-c44fe5fac7ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_4524bbd5-07e5-4b08-b92f-6901d4557a53" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_98e9bf54-9467-467d-82c1-c44fe5fac7ca" xlink:to="loc_us-gaap_LineOfCreditMember_4524bbd5-07e5-4b08-b92f-6901d4557a53" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_b0a29597-2339-4698-80db-0f759433595e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d63c1b42-07a1-4f9d-8d4e-e09a010f0db7" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_b0a29597-2339-4698-80db-0f759433595e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_b0a29597-2339-4698-80db-0f759433595e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_b0a29597-2339-4698-80db-0f759433595e" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_b0a29597-2339-4698-80db-0f759433595e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_3276fe2e-10ed-4ae1-8439-524c37652528" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_b0a29597-2339-4698-80db-0f759433595e" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_3276fe2e-10ed-4ae1-8439-524c37652528" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_SyndicateOfLendersMember_aab67bc6-3dac-426d-ae38-ce160e43dec4" xlink:href="prth-20200930.xsd#prth_SyndicateOfLendersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_3276fe2e-10ed-4ae1-8439-524c37652528" xlink:to="loc_prth_SyndicateOfLendersMember_aab67bc6-3dac-426d-ae38-ce160e43dec4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_GoldmanSachsSpecialtyLendingGroupMember_3f69c454-8322-4ec7-8123-1c294a6f442b" xlink:href="prth-20200930.xsd#prth_GoldmanSachsSpecialtyLendingGroupMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_3276fe2e-10ed-4ae1-8439-524c37652528" xlink:to="loc_prth_GoldmanSachsSpecialtyLendingGroupMember_3f69c454-8322-4ec7-8123-1c294a6f442b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_1c446e3a-35d0-4547-9b32-5d7a5b3d8fd8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d63c1b42-07a1-4f9d-8d4e-e09a010f0db7" xlink:to="loc_us-gaap_CreditFacilityAxis_1c446e3a-35d0-4547-9b32-5d7a5b3d8fd8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_1c446e3a-35d0-4547-9b32-5d7a5b3d8fd8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_1c446e3a-35d0-4547-9b32-5d7a5b3d8fd8" xlink:to="loc_us-gaap_CreditFacilityDomain_1c446e3a-35d0-4547-9b32-5d7a5b3d8fd8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_40c81d01-a6d6-483b-a810-f3f43073c84b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_1c446e3a-35d0-4547-9b32-5d7a5b3d8fd8" xlink:to="loc_us-gaap_CreditFacilityDomain_40c81d01-a6d6-483b-a810-f3f43073c84b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_TermLoanMember_6206ac6a-2d4a-4360-b81f-1837d53d7eeb" xlink:href="prth-20200930.xsd#prth_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_40c81d01-a6d6-483b-a810-f3f43073c84b" xlink:to="loc_prth_TermLoanMember_6206ac6a-2d4a-4360-b81f-1837d53d7eeb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_c954b523-87e7-4764-b16f-2dfbd07c026e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_40c81d01-a6d6-483b-a810-f3f43073c84b" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_c954b523-87e7-4764-b16f-2dfbd07c026e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/DEBTOBLIGATIONSEffectiveInterestRatesDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#DEBTOBLIGATIONSEffectiveInterestRatesDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/DEBTOBLIGATIONSEffectiveInterestRatesDetails" xlink:type="extended" id="iecc43ac045d94633bc0a28c24e588a66_DEBTOBLIGATIONSEffectiveInterestRatesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_2888dbd7-8435-43a8-9cab-a77ae7e49e04" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateDuringPeriod_249317d7-d38f-4da3-b40e-548aa562304f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2888dbd7-8435-43a8-9cab-a77ae7e49e04" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateDuringPeriod_249317d7-d38f-4da3-b40e-548aa562304f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_96c6e1da-f705-4468-a894-76ca200145d0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2888dbd7-8435-43a8-9cab-a77ae7e49e04" xlink:to="loc_us-gaap_DebtInstrumentTable_96c6e1da-f705-4468-a894-76ca200145d0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_1050e62a-d4c5-4725-8e2a-9b780f6909da" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_96c6e1da-f705-4468-a894-76ca200145d0" xlink:to="loc_us-gaap_CreditFacilityAxis_1050e62a-d4c5-4725-8e2a-9b780f6909da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_1050e62a-d4c5-4725-8e2a-9b780f6909da_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_1050e62a-d4c5-4725-8e2a-9b780f6909da" xlink:to="loc_us-gaap_CreditFacilityDomain_1050e62a-d4c5-4725-8e2a-9b780f6909da_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_4cf62401-8d20-409b-91b9-1bfa5127b0d2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_1050e62a-d4c5-4725-8e2a-9b780f6909da" xlink:to="loc_us-gaap_CreditFacilityDomain_4cf62401-8d20-409b-91b9-1bfa5127b0d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_fb70897b-fdbc-4c8f-84da-c3cd9cb5aa03" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_4cf62401-8d20-409b-91b9-1bfa5127b0d2" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_fb70897b-fdbc-4c8f-84da-c3cd9cb5aa03" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_6b646450-a936-4b9f-a6d0-b84105f45c50" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_96c6e1da-f705-4468-a894-76ca200145d0" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_6b646450-a936-4b9f-a6d0-b84105f45c50" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_6b646450-a936-4b9f-a6d0-b84105f45c50_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_6b646450-a936-4b9f-a6d0-b84105f45c50" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_6b646450-a936-4b9f-a6d0-b84105f45c50_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_085e2363-d82e-4840-8937-a6beb36a8d02" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_6b646450-a936-4b9f-a6d0-b84105f45c50" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_085e2363-d82e-4840-8937-a6beb36a8d02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_SyndicateOfLendersMember_e0f32dbb-6fc6-47a3-9809-1aa2b940b0bf" xlink:href="prth-20200930.xsd#prth_SyndicateOfLendersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_085e2363-d82e-4840-8937-a6beb36a8d02" xlink:to="loc_prth_SyndicateOfLendersMember_e0f32dbb-6fc6-47a3-9809-1aa2b940b0bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_GoldmanSachsSpecialtyLendingGroupMember_91fe8487-772b-40d0-8e21-479253762c68" xlink:href="prth-20200930.xsd#prth_GoldmanSachsSpecialtyLendingGroupMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_085e2363-d82e-4840-8937-a6beb36a8d02" xlink:to="loc_prth_GoldmanSachsSpecialtyLendingGroupMember_91fe8487-772b-40d0-8e21-479253762c68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_90e55396-be12-437a-b7f0-beda8282d2f0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_96c6e1da-f705-4468-a894-76ca200145d0" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_90e55396-be12-437a-b7f0-beda8282d2f0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_90e55396-be12-437a-b7f0-beda8282d2f0_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_90e55396-be12-437a-b7f0-beda8282d2f0" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_90e55396-be12-437a-b7f0-beda8282d2f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_95254866-06e0-4b76-9cae-5bf570404832" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_90e55396-be12-437a-b7f0-beda8282d2f0" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_95254866-06e0-4b76-9cae-5bf570404832" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_d114face-ae76-426a-b641-fb772931fcdf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_95254866-06e0-4b76-9cae-5bf570404832" xlink:to="loc_us-gaap_LineOfCreditMember_d114face-ae76-426a-b641-fb772931fcdf" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/INCOMETAXES" xlink:type="simple" xlink:href="prth-20200930.xsd#INCOMETAXES"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/INCOMETAXES" xlink:type="extended" id="i016cd6e74d064d6e9c549eca6157682c_INCOMETAXES"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/INCOMETAXESTables" xlink:type="simple" xlink:href="prth-20200930.xsd#INCOMETAXESTables"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/INCOMETAXESTables" xlink:type="extended" id="i502a51554e824186a9fd7a47ca90b56d_INCOMETAXESTables"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/INCOMETAXESScheduleofIncomeTaxBenefitProvisionDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#INCOMETAXESScheduleofIncomeTaxBenefitProvisionDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/INCOMETAXESScheduleofIncomeTaxBenefitProvisionDetails" xlink:type="extended" id="ib559f7ba786d4db49920bcfdc5b703fb_INCOMETAXESScheduleofIncomeTaxBenefitProvisionDetails"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/INCOMETAXESNarrativeDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#INCOMETAXESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/INCOMETAXESNarrativeDetails" xlink:type="extended" id="id294e1cbdf56498fbc85963c83c1b0c7_INCOMETAXESNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceLineItems_1bb8cb7e-7ee7-4e79-a75c-85203394c2e4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowanceLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_f8f29c82-9c46-4a9d-b21a-b2430d7d571f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowanceLineItems_1bb8cb7e-7ee7-4e79-a75c-85203394c2e4" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_f8f29c82-9c46-4a9d-b21a-b2430d7d571f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_1b5afdeb-8c64-478e-af9b-d04671101355" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowanceLineItems_1bb8cb7e-7ee7-4e79-a75c-85203394c2e4" xlink:to="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_1b5afdeb-8c64-478e-af9b-d04671101355" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_5b9a605e-77a8-43dc-b3d5-743c5cc5db96" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowanceLineItems_1bb8cb7e-7ee7-4e79-a75c-85203394c2e4" xlink:to="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_5b9a605e-77a8-43dc-b3d5-743c5cc5db96" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredOtherTaxExpenseBenefit_3811f3a2-9abf-495b-a1fe-b59dad0f9834" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredOtherTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowanceLineItems_1bb8cb7e-7ee7-4e79-a75c-85203394c2e4" xlink:to="loc_us-gaap_DeferredOtherTaxExpenseBenefit_3811f3a2-9abf-495b-a1fe-b59dad0f9834" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability_e9bd46b7-63be-4a5e-8afe-dd93eab95cf4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowanceLineItems_1bb8cb7e-7ee7-4e79-a75c-85203394c2e4" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability_e9bd46b7-63be-4a5e-8afe-dd93eab95cf4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceTable_e73ddddf-d856-4c28-b9f4-3114a122ee89" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowanceTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ValuationAllowanceLineItems_1bb8cb7e-7ee7-4e79-a75c-85203394c2e4" xlink:to="loc_us-gaap_ValuationAllowanceTable_e73ddddf-d856-4c28-b9f4-3114a122ee89" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_0b6cfa85-aaaa-4448-bd10-395f549079b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ValuationAllowanceTable_e73ddddf-d856-4c28-b9f4-3114a122ee89" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_0b6cfa85-aaaa-4448-bd10-395f549079b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0b6cfa85-aaaa-4448-bd10-395f549079b9_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_0b6cfa85-aaaa-4448-bd10-395f549079b9" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0b6cfa85-aaaa-4448-bd10-395f549079b9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_c7c2bcfd-cd94-4fd5-b1cf-624483b8d1f7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_0b6cfa85-aaaa-4448-bd10-395f549079b9" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_c7c2bcfd-cd94-4fd5-b1cf-624483b8d1f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_a4edd57e-6d54-4b21-9ef6-85c0908b2475" xlink:href="prth-20200930.xsd#prth_PriorityRealEstateTechnologyLLCPRETMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_c7c2bcfd-cd94-4fd5-b1cf-624483b8d1f7" xlink:to="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_a4edd57e-6d54-4b21-9ef6-85c0908b2475" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitAxis_c384d730-1f2e-4468-9aa2-41868d44b514" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ValuationAllowanceTable_e73ddddf-d856-4c28-b9f4-3114a122ee89" xlink:to="loc_us-gaap_ReportingUnitAxis_c384d730-1f2e-4468-9aa2-41868d44b514" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_c384d730-1f2e-4468-9aa2-41868d44b514_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReportingUnitAxis_c384d730-1f2e-4468-9aa2-41868d44b514" xlink:to="loc_us-gaap_ReportingUnitDomain_c384d730-1f2e-4468-9aa2-41868d44b514_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_a4d434c6-7ea9-4da7-905d-19bc73cf78d8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReportingUnitAxis_c384d730-1f2e-4468-9aa2-41868d44b514" xlink:to="loc_us-gaap_ReportingUnitDomain_a4d434c6-7ea9-4da7-905d-19bc73cf78d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_IntegratedPartnersRentPaymentComponentMember_ce90a0c7-f7b4-42f8-b856-880770e5445f" xlink:href="prth-20200930.xsd#prth_IntegratedPartnersRentPaymentComponentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_a4d434c6-7ea9-4da7-905d-19bc73cf78d8" xlink:to="loc_prth_IntegratedPartnersRentPaymentComponentMember_ce90a0c7-f7b4-42f8-b856-880770e5445f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/COMMITMENTSANDCONTINGENCIES" xlink:type="simple" xlink:href="prth-20200930.xsd#COMMITMENTSANDCONTINGENCIES"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/COMMITMENTSANDCONTINGENCIES" xlink:type="extended" id="i95d2f25be7cc4e3089350db0c8f63533_COMMITMENTSANDCONTINGENCIES"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/COMMITMENTSANDCONTINGENCIESNarrativeDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#COMMITMENTSANDCONTINGENCIESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/COMMITMENTSANDCONTINGENCIESNarrativeDetails" xlink:type="extended" id="if325e93b9a52493aa42ddb30b66a803e_COMMITMENTSANDCONTINGENCIESNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_prth_ScheduleofAssetAcquisitionLineItems_b6acc690-26a8-489e-a279-644875a10342" xlink:href="prth-20200930.xsd#prth_ScheduleofAssetAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentAmount_5a9ac8b1-e336-4e90-8d67-84e59d1f67ef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermPurchaseCommitmentAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_b6acc690-26a8-489e-a279-644875a10342" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentAmount_5a9ac8b1-e336-4e90-8d67-84e59d1f67ef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_NumberofAgreements_aeab0c1a-c2ff-4502-8a58-f6f919d1550b" xlink:href="prth-20200930.xsd#prth_NumberofAgreements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_b6acc690-26a8-489e-a279-644875a10342" xlink:to="loc_prth_NumberofAgreements_aeab0c1a-c2ff-4502-8a58-f6f919d1550b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ResellerArrangementPeriod_9cadc626-8428-471f-876d-94cdfd41d6d2" xlink:href="prth-20200930.xsd#prth_ResellerArrangementPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_b6acc690-26a8-489e-a279-644875a10342" xlink:to="loc_prth_ResellerArrangementPeriod_9cadc626-8428-471f-876d-94cdfd41d6d2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_AssetAcquisitionContingentConsideration_8af32f27-253e-44ad-918a-6c8ef6591b6a" xlink:href="prth-20200930.xsd#prth_AssetAcquisitionContingentConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_b6acc690-26a8-489e-a279-644875a10342" xlink:to="loc_prth_AssetAcquisitionContingentConsideration_8af32f27-253e-44ad-918a-6c8ef6591b6a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_AssetAcquisitionIntangibleAssets_457b5cef-fb11-4abd-a438-128e48c61976" xlink:href="prth-20200930.xsd#prth_AssetAcquisitionIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_b6acc690-26a8-489e-a279-644875a10342" xlink:to="loc_prth_AssetAcquisitionIntangibleAssets_457b5cef-fb11-4abd-a438-128e48c61976" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_454ca386-934d-4069-800e-b13bf1a39acc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_b6acc690-26a8-489e-a279-644875a10342" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_454ca386-934d-4069-800e-b13bf1a39acc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ContingentCashPaymentsForAssetAcquisitions_2b3a315c-7167-4868-aac2-9a469fcdd789" xlink:href="prth-20200930.xsd#prth_ContingentCashPaymentsForAssetAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_b6acc690-26a8-489e-a279-644875a10342" xlink:to="loc_prth_ContingentCashPaymentsForAssetAcquisitions_2b3a315c-7167-4868-aac2-9a469fcdd789" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ScheduleOfAssetAcquisitionTable_fdf6d14f-53bb-4ad7-b385-b4318a8a0542" xlink:href="prth-20200930.xsd#prth_ScheduleOfAssetAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_b6acc690-26a8-489e-a279-644875a10342" xlink:to="loc_prth_ScheduleOfAssetAcquisitionTable_fdf6d14f-53bb-4ad7-b385-b4318a8a0542" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_dcd7c5d3-cb6d-43a2-b936-d814ba8de2d0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleOfAssetAcquisitionTable_fdf6d14f-53bb-4ad7-b385-b4318a8a0542" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_dcd7c5d3-cb6d-43a2-b936-d814ba8de2d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_dcd7c5d3-cb6d-43a2-b936-d814ba8de2d0_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_dcd7c5d3-cb6d-43a2-b936-d814ba8de2d0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_dcd7c5d3-cb6d-43a2-b936-d814ba8de2d0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_df5c685b-ca42-47de-8e2e-c237d484d2dd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_dcd7c5d3-cb6d-43a2-b936-d814ba8de2d0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_df5c685b-ca42-47de-8e2e-c237d484d2dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceAgreementsMember_28e6bb98-5c5d-46ea-a85b-f5b597c3ba40" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ServiceAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_df5c685b-ca42-47de-8e2e-c237d484d2dd" xlink:to="loc_us-gaap_ServiceAgreementsMember_28e6bb98-5c5d-46ea-a85b-f5b597c3ba40" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_c60b0a92-1b99-4d0d-9961-b2df1bb5d0a5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleOfAssetAcquisitionTable_fdf6d14f-53bb-4ad7-b385-b4318a8a0542" xlink:to="loc_us-gaap_CreditFacilityAxis_c60b0a92-1b99-4d0d-9961-b2df1bb5d0a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_c60b0a92-1b99-4d0d-9961-b2df1bb5d0a5_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_c60b0a92-1b99-4d0d-9961-b2df1bb5d0a5" xlink:to="loc_us-gaap_CreditFacilityDomain_c60b0a92-1b99-4d0d-9961-b2df1bb5d0a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_4b224844-98a5-4115-910e-b2518ede659f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_c60b0a92-1b99-4d0d-9961-b2df1bb5d0a5" xlink:to="loc_us-gaap_CreditFacilityDomain_4b224844-98a5-4115-910e-b2518ede659f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_TermLoanMember_08fc54b2-3bc9-40e7-b837-3282f0e3150d" xlink:href="prth-20200930.xsd#prth_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_4b224844-98a5-4115-910e-b2518ede659f" xlink:to="loc_prth_TermLoanMember_08fc54b2-3bc9-40e7-b837-3282f0e3150d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_c6cb0ee9-21d9-4b2a-96fd-318c59311fda" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_4b224844-98a5-4115-910e-b2518ede659f" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_c6cb0ee9-21d9-4b2a-96fd-318c59311fda" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_e866d413-a003-422d-98ae-97c5e9b3ab75" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleOfAssetAcquisitionTable_fdf6d14f-53bb-4ad7-b385-b4318a8a0542" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_e866d413-a003-422d-98ae-97c5e9b3ab75" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_e866d413-a003-422d-98ae-97c5e9b3ab75_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_e866d413-a003-422d-98ae-97c5e9b3ab75" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_e866d413-a003-422d-98ae-97c5e9b3ab75_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_dba043de-00d4-482e-be98-f6c7039ee87e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_e866d413-a003-422d-98ae-97c5e9b3ab75" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_dba043de-00d4-482e-be98-f6c7039ee87e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_SyndicateOfLendersMember_acba4a58-0a06-416e-a26f-6d27ca4000d3" xlink:href="prth-20200930.xsd#prth_SyndicateOfLendersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_dba043de-00d4-482e-be98-f6c7039ee87e" xlink:to="loc_prth_SyndicateOfLendersMember_acba4a58-0a06-416e-a26f-6d27ca4000d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_6375fae7-7088-4b07-8a0f-a3c8b644b3c3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleOfAssetAcquisitionTable_fdf6d14f-53bb-4ad7-b385-b4318a8a0542" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_6375fae7-7088-4b07-8a0f-a3c8b644b3c3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_6375fae7-7088-4b07-8a0f-a3c8b644b3c3_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_6375fae7-7088-4b07-8a0f-a3c8b644b3c3" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_6375fae7-7088-4b07-8a0f-a3c8b644b3c3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_23393f34-d1e1-4233-a920-b12b020fd48a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_6375fae7-7088-4b07-8a0f-a3c8b644b3c3" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_23393f34-d1e1-4233-a920-b12b020fd48a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_25e120c6-f477-4aea-bece-a05751813839" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_23393f34-d1e1-4233-a920-b12b020fd48a" xlink:to="loc_us-gaap_LineOfCreditMember_25e120c6-f477-4aea-bece-a05751813839" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/RELATEDPARTYTRANSACTIONS" xlink:type="simple" xlink:href="prth-20200930.xsd#RELATEDPARTYTRANSACTIONS"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/RELATEDPARTYTRANSACTIONS" xlink:type="extended" id="i3923722cf3a343af9016956ff57bbfce_RELATEDPARTYTRANSACTIONS"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/RELATEDPARTYTRANSACTIONSNarrativeDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#RELATEDPARTYTRANSACTIONSNarrativeDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/RELATEDPARTYTRANSACTIONSNarrativeDetails" xlink:type="extended" id="ice7a43aa0bfe45b8a442c8e4e609b84c_RELATEDPARTYTRANSACTIONSNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_569640ae-619a-41cf-97ed-1dde36ef8662" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesAndLoansReceivableGrossNoncurrent_893d62b4-33c6-4efb-983b-a6f9e3f402fa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NotesAndLoansReceivableGrossNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_569640ae-619a-41cf-97ed-1dde36ef8662" xlink:to="loc_us-gaap_NotesAndLoansReceivableGrossNoncurrent_893d62b4-33c6-4efb-983b-a6f9e3f402fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_NotesLoansAndFinancingReceivableGrossMaximumLoanCommitmentAvailableForFutureIssuanceNoncurrent_8fc049aa-a4f0-47f0-bd4b-aead9a5596c5" xlink:href="prth-20200930.xsd#prth_NotesLoansAndFinancingReceivableGrossMaximumLoanCommitmentAvailableForFutureIssuanceNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_569640ae-619a-41cf-97ed-1dde36ef8662" xlink:to="loc_prth_NotesLoansAndFinancingReceivableGrossMaximumLoanCommitmentAvailableForFutureIssuanceNoncurrent_8fc049aa-a4f0-47f0-bd4b-aead9a5596c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_NotesLoansAndFinancingReceivableGrossNoncurrentAnnualInterestRate_ef7759a4-f393-43a7-90e9-011df00707a3" xlink:href="prth-20200930.xsd#prth_NotesLoansAndFinancingReceivableGrossNoncurrentAnnualInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_569640ae-619a-41cf-97ed-1dde36ef8662" xlink:to="loc_prth_NotesLoansAndFinancingReceivableGrossNoncurrentAnnualInterestRate_ef7759a4-f393-43a7-90e9-011df00707a3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeRelatedParty_bab00494-9d54-46f5-86e5-aa59cda83ee0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestIncomeRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_569640ae-619a-41cf-97ed-1dde36ef8662" xlink:to="loc_us-gaap_InterestIncomeRelatedParty_bab00494-9d54-46f5-86e5-aa59cda83ee0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PercentageOfOwnershipBeforeTransaction_ba620cc3-ce93-4c5c-af27-4375066c8637" xlink:href="prth-20200930.xsd#prth_PercentageOfOwnershipBeforeTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_569640ae-619a-41cf-97ed-1dde36ef8662" xlink:to="loc_prth_PercentageOfOwnershipBeforeTransaction_ba620cc3-ce93-4c5c-af27-4375066c8637" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableNoncontrollingInterestEquityPreferredRedemptionValue_17c8e57d-e261-4fea-8b60-c7c7694d201b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RedeemableNoncontrollingInterestEquityPreferredRedemptionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_569640ae-619a-41cf-97ed-1dde36ef8662" xlink:to="loc_us-gaap_RedeemableNoncontrollingInterestEquityPreferredRedemptionValue_17c8e57d-e261-4fea-8b60-c7c7694d201b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_RedeemableNoncontrollingInterestEquityPreferredAnnualPreferredYieldPercent_d5d06f3b-b487-4ebc-a24e-db3d5c4b6cfe" xlink:href="prth-20200930.xsd#prth_RedeemableNoncontrollingInterestEquityPreferredAnnualPreferredYieldPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_569640ae-619a-41cf-97ed-1dde36ef8662" xlink:to="loc_prth_RedeemableNoncontrollingInterestEquityPreferredAnnualPreferredYieldPercent_d5d06f3b-b487-4ebc-a24e-db3d5c4b6cfe" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PreferredStockPercentageOwned_d700165f-c3ad-434d-a37e-3cc251729d07" xlink:href="prth-20200930.xsd#prth_PreferredStockPercentageOwned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_569640ae-619a-41cf-97ed-1dde36ef8662" xlink:to="loc_prth_PreferredStockPercentageOwned_d700165f-c3ad-434d-a37e-3cc251729d07" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_84d7af0a-5fc3-47fe-bdc9-e1b47610cd11" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_569640ae-619a-41cf-97ed-1dde36ef8662" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_84d7af0a-5fc3-47fe-bdc9-e1b47610cd11" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_fadaba4d-5cf5-470e-88ae-a489d866f23b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_569640ae-619a-41cf-97ed-1dde36ef8662" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_fadaba4d-5cf5-470e-88ae-a489d866f23b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_b8be3979-2377-4097-8b61-a12e5e3dcbfe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_569640ae-619a-41cf-97ed-1dde36ef8662" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_b8be3979-2377-4097-8b61-a12e5e3dcbfe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_fa76ed40-9a91-4cae-a6f7-2d3b95bd5062" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_b8be3979-2377-4097-8b61-a12e5e3dcbfe" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_fa76ed40-9a91-4cae-a6f7-2d3b95bd5062" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_fa76ed40-9a91-4cae-a6f7-2d3b95bd5062_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_fa76ed40-9a91-4cae-a6f7-2d3b95bd5062" xlink:to="loc_us-gaap_RelatedPartyDomain_fa76ed40-9a91-4cae-a6f7-2d3b95bd5062_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_62f76bdb-2eee-4250-a305-90ca061e6c38" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_fa76ed40-9a91-4cae-a6f7-2d3b95bd5062" xlink:to="loc_us-gaap_RelatedPartyDomain_62f76bdb-2eee-4250-a305-90ca061e6c38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ChiefExecutiveOfficerAndChairmanMember_b29aa7f4-f061-4bc5-be64-f4b5b7d4b57b" xlink:href="prth-20200930.xsd#prth_ChiefExecutiveOfficerAndChairmanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_62f76bdb-2eee-4250-a305-90ca061e6c38" xlink:to="loc_prth_ChiefExecutiveOfficerAndChairmanMember_b29aa7f4-f061-4bc5-be64-f4b5b7d4b57b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_10b53bbb-9191-4dc3-8173-1b0c549f705c" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_b8be3979-2377-4097-8b61-a12e5e3dcbfe" xlink:to="loc_dei_LegalEntityAxis_10b53bbb-9191-4dc3-8173-1b0c549f705c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_10b53bbb-9191-4dc3-8173-1b0c549f705c_default" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_10b53bbb-9191-4dc3-8173-1b0c549f705c" xlink:to="loc_dei_EntityDomain_10b53bbb-9191-4dc3-8173-1b0c549f705c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_eaab2870-e7e5-4338-812d-d5d488141bfc" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_10b53bbb-9191-4dc3-8173-1b0c549f705c" xlink:to="loc_dei_EntityDomain_eaab2870-e7e5-4338-812d-d5d488141bfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PriorityHospitalityTechnologyLLCMember_3b817231-599e-4a5a-a5db-fa46d1de37b4" xlink:href="prth-20200930.xsd#prth_PriorityHospitalityTechnologyLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_eaab2870-e7e5-4338-812d-d5d488141bfc" xlink:to="loc_prth_PriorityHospitalityTechnologyLLCMember_3b817231-599e-4a5a-a5db-fa46d1de37b4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTEREST" xlink:type="simple" xlink:href="prth-20200930.xsd#RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTEREST"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTEREST" xlink:type="extended" id="i016644cd4fef4ac1b8f80adf0645b3ff_RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTEREST"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTERESTTables" xlink:type="simple" xlink:href="prth-20200930.xsd#RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTERESTTables"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTERESTTables" xlink:type="extended" id="i3736ff79c5d74ebb9612bb5b8e9a625d_RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTERESTTables"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTERESTNarrativeDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTERESTNarrativeDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTERESTNarrativeDetails" xlink:type="extended" id="i1f3cc3f4c1574f9696c9dc0d419ed409_RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTERESTNarrativeDetails"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTERESTEquityReconciliationDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTERESTEquityReconciliationDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTERESTEquityReconciliationDetails" xlink:type="extended" id="i596d0ebfc819409395477801553f6ea1_RECONCILIATIONOFSTOCKHOLDERSDEFICITANDNONCONTROLLINGINTERESTEquityReconciliationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_a8a85dc4-d0be-4a63-9761-6019deb686e6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_a8a85dc4-d0be-4a63-9761-6019deb686e6" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_191ae043-9128-4831-bda4-1d155df34e89" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:to="loc_us-gaap_SharesOutstanding_191ae043-9128-4831-bda4-1d155df34e89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_e031c566-493f-4180-8cc3-3d7b80848092" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_e031c566-493f-4180-8cc3-3d7b80848092" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_1f8642d7-cf0b-4ebb-bd9f-2c385b09cdb6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_1f8642d7-cf0b-4ebb-bd9f-2c385b09cdb6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_f17ba779-68a8-4ef2-8e16-d31d35dafeef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_f17ba779-68a8-4ef2-8e16-d31d35dafeef" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_5c2d1c59-0592-4340-b686-ce51a968b02a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_5c2d1c59-0592-4340-b686-ce51a968b02a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_c6b8625c-6cc0-4769-a31c-7e4d9ebd9d41" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_c6b8625c-6cc0-4769-a31c-7e4d9ebd9d41" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_fd803ed1-7b09-40e0-bca7-83ca5fcd26e2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_fd803ed1-7b09-40e0-bca7-83ca5fcd26e2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_e2f5d388-e2d3-4edb-a0fd-50784345bded" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:to="loc_us-gaap_NetIncomeLoss_e2f5d388-e2d3-4edb-a0fd-50784345bded" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromRedemptions_72266295-f560-4a77-b0d5-bca793ff5630" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterestDecreaseFromRedemptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromRedemptions_72266295-f560-4a77-b0d5-bca793ff5630" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_b039afeb-4271-4632-b3c8-ed9cae8cd0f5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_b039afeb-4271-4632-b3c8-ed9cae8cd0f5" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance_b694b300-6854-4a69-a0c9-e9ace497be1d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_172be5aa-e4ac-4df9-a18f-9d40d4414ee0" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance_b694b300-6854-4a69-a0c9-e9ace497be1d" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_018544b6-1dbf-4d30-9afe-3a3404682b12" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_4ec47fc3-64b4-4ffb-806e-175a03c60998" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_2695929b-c4e0-4904-a4d0-59c7d07031ae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_a8a85dc4-d0be-4a63-9761-6019deb686e6" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_2695929b-c4e0-4904-a4d0-59c7d07031ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightOutstanding_9c5b4fda-0bcf-4692-9b80-633a96c90f0a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_a8a85dc4-d0be-4a63-9761-6019deb686e6" xlink:to="loc_us-gaap_ClassOfWarrantOrRightOutstanding_9c5b4fda-0bcf-4692-9b80-633a96c90f0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_271f3492-f500-4e2d-8cbe-c3909bd95b39" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_a8a85dc4-d0be-4a63-9761-6019deb686e6" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_271f3492-f500-4e2d-8cbe-c3909bd95b39" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_83913273-8700-45f6-b15a-66d8864219c9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_a8a85dc4-d0be-4a63-9761-6019deb686e6" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_83913273-8700-45f6-b15a-66d8864219c9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_GainLossOnDispositionOfBusinessAttributableToNoncontrollingInterest_62c4b023-2ae4-4a53-a4b2-b5f62f939e24" xlink:href="prth-20200930.xsd#prth_GainLossOnDispositionOfBusinessAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_a8a85dc4-d0be-4a63-9761-6019deb686e6" xlink:to="loc_prth_GainLossOnDispositionOfBusinessAttributableToNoncontrollingInterest_62c4b023-2ae4-4a53-a4b2-b5f62f939e24" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_c68b304b-4bcc-42a3-a91f-9015ec65a0c2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_a8a85dc4-d0be-4a63-9761-6019deb686e6" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_c68b304b-4bcc-42a3-a91f-9015ec65a0c2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_b469a0ad-4d66-43b6-936c-e913672507b1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_a8a85dc4-d0be-4a63-9761-6019deb686e6" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_b469a0ad-4d66-43b6-936c-e913672507b1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_fd6c6d13-30a9-4bf2-9f02-259fc43740d3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_b469a0ad-4d66-43b6-936c-e913672507b1" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_fd6c6d13-30a9-4bf2-9f02-259fc43740d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_fd6c6d13-30a9-4bf2-9f02-259fc43740d3_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_fd6c6d13-30a9-4bf2-9f02-259fc43740d3" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_fd6c6d13-30a9-4bf2-9f02-259fc43740d3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_9a2f8782-a020-4e19-a877-34480eb184e9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_fd6c6d13-30a9-4bf2-9f02-259fc43740d3" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_9a2f8782-a020-4e19-a877-34480eb184e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_MIAcquisitionsWarrantsPublicMember_087f99a0-0366-4d82-ac59-82fd8b02965c" xlink:href="prth-20200930.xsd#prth_MIAcquisitionsWarrantsPublicMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_9a2f8782-a020-4e19-a877-34480eb184e9" xlink:to="loc_prth_MIAcquisitionsWarrantsPublicMember_087f99a0-0366-4d82-ac59-82fd8b02965c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_MIAcquisitionsWarrantsPrivateMember_8490c08e-1c90-4357-aa99-4697089684bb" xlink:href="prth-20200930.xsd#prth_MIAcquisitionsWarrantsPrivateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_9a2f8782-a020-4e19-a877-34480eb184e9" xlink:to="loc_prth_MIAcquisitionsWarrantsPrivateMember_8490c08e-1c90-4357-aa99-4697089684bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_6649d6d9-66d0-4df6-854c-82e0f931efe2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_b469a0ad-4d66-43b6-936c-e913672507b1" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_6649d6d9-66d0-4df6-854c-82e0f931efe2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_6649d6d9-66d0-4df6-854c-82e0f931efe2_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_6649d6d9-66d0-4df6-854c-82e0f931efe2" xlink:to="loc_us-gaap_EquityComponentDomain_6649d6d9-66d0-4df6-854c-82e0f931efe2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_c04f6c39-43e2-4490-a715-a2e98131696e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_6649d6d9-66d0-4df6-854c-82e0f931efe2" xlink:to="loc_us-gaap_EquityComponentDomain_c04f6c39-43e2-4490-a715-a2e98131696e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_b503da05-06a7-4355-a7f1-78bfd33f46cc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_c04f6c39-43e2-4490-a715-a2e98131696e" xlink:to="loc_us-gaap_PreferredStockMember_b503da05-06a7-4355-a7f1-78bfd33f46cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_95e2fefd-29de-4914-a067-44417158d0d6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_c04f6c39-43e2-4490-a715-a2e98131696e" xlink:to="loc_us-gaap_CommonStockMember_95e2fefd-29de-4914-a067-44417158d0d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockMember_ad9c4978-ed8d-4941-94b8-2c471128fa40" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_c04f6c39-43e2-4490-a715-a2e98131696e" xlink:to="loc_us-gaap_TreasuryStockMember_ad9c4978-ed8d-4941-94b8-2c471128fa40" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_ea6ee2aa-dc4a-42b3-9b8a-5fe84359999b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_c04f6c39-43e2-4490-a715-a2e98131696e" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_ea6ee2aa-dc4a-42b3-9b8a-5fe84359999b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_9718b28d-410c-49bf-bf23-7ef9fc4baf5d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_c04f6c39-43e2-4490-a715-a2e98131696e" xlink:to="loc_us-gaap_RetainedEarningsMember_9718b28d-410c-49bf-bf23-7ef9fc4baf5d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParentMember_ca0adc4a-d30b-4fd6-9322-093c55c2b8ca" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_c04f6c39-43e2-4490-a715-a2e98131696e" xlink:to="loc_us-gaap_ParentMember_ca0adc4a-d30b-4fd6-9322-093c55c2b8ca" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_f1423f5d-dae8-43b7-a516-d1504cbec07a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_c04f6c39-43e2-4490-a715-a2e98131696e" xlink:to="loc_us-gaap_NoncontrollingInterestMember_f1423f5d-dae8-43b7-a516-d1504cbec07a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_4a1eda63-db11-4493-bde5-0d45bbea53db" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_b469a0ad-4d66-43b6-936c-e913672507b1" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_4a1eda63-db11-4493-bde5-0d45bbea53db" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_4a1eda63-db11-4493-bde5-0d45bbea53db_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_4a1eda63-db11-4493-bde5-0d45bbea53db" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_4a1eda63-db11-4493-bde5-0d45bbea53db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_fbaeec1c-4e6e-4d67-8386-3726947fdbbc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_4a1eda63-db11-4493-bde5-0d45bbea53db" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_fbaeec1c-4e6e-4d67-8386-3726947fdbbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_b03a574b-ca78-441a-949f-ad200da1d399" xlink:href="prth-20200930.xsd#prth_PriorityRealEstateTechnologyLLCPRETMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_fbaeec1c-4e6e-4d67-8386-3726947fdbbc" xlink:to="loc_prth_PriorityRealEstateTechnologyLLCPRETMember_b03a574b-ca78-441a-949f-ad200da1d399" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitAxis_a520ca42-5c91-46ba-8d8d-da57054c9cd1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_b469a0ad-4d66-43b6-936c-e913672507b1" xlink:to="loc_us-gaap_ReportingUnitAxis_a520ca42-5c91-46ba-8d8d-da57054c9cd1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_a520ca42-5c91-46ba-8d8d-da57054c9cd1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReportingUnitAxis_a520ca42-5c91-46ba-8d8d-da57054c9cd1" xlink:to="loc_us-gaap_ReportingUnitDomain_a520ca42-5c91-46ba-8d8d-da57054c9cd1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_3a03ef66-3c67-41d6-920a-7096c46e9ec2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReportingUnitAxis_a520ca42-5c91-46ba-8d8d-da57054c9cd1" xlink:to="loc_us-gaap_ReportingUnitDomain_3a03ef66-3c67-41d6-920a-7096c46e9ec2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_IntegratedPartnersRentPaymentComponentMember_85f1ff97-1989-40c5-a6bd-0f76b066ab04" xlink:href="prth-20200930.xsd#prth_IntegratedPartnersRentPaymentComponentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_3a03ef66-3c67-41d6-920a-7096c46e9ec2" xlink:to="loc_prth_IntegratedPartnersRentPaymentComponentMember_85f1ff97-1989-40c5-a6bd-0f76b066ab04" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_aa60c8bf-ef0d-410b-aa5b-3ab39d599caa" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_b469a0ad-4d66-43b6-936c-e913672507b1" xlink:to="loc_dei_LegalEntityAxis_aa60c8bf-ef0d-410b-aa5b-3ab39d599caa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_aa60c8bf-ef0d-410b-aa5b-3ab39d599caa_default" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_aa60c8bf-ef0d-410b-aa5b-3ab39d599caa" xlink:to="loc_dei_EntityDomain_aa60c8bf-ef0d-410b-aa5b-3ab39d599caa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_ef8fd7bb-ccb1-4189-818f-473b0bc6412a" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_aa60c8bf-ef0d-410b-aa5b-3ab39d599caa" xlink:to="loc_dei_EntityDomain_ef8fd7bb-ccb1-4189-818f-473b0bc6412a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PriorityHospitalityTechnologyLLCMember_9c82d7f4-9d85-4809-a081-5b846a09ecc8" xlink:href="prth-20200930.xsd#prth_PriorityHospitalityTechnologyLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_ef8fd7bb-ccb1-4189-818f-473b0bc6412a" xlink:to="loc_prth_PriorityHospitalityTechnologyLLCMember_9c82d7f4-9d85-4809-a081-5b846a09ecc8" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/STOCKBASEDCOMPENSATIONPLANS" xlink:type="simple" xlink:href="prth-20200930.xsd#STOCKBASEDCOMPENSATIONPLANS"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/STOCKBASEDCOMPENSATIONPLANS" xlink:type="extended" id="ibc240ad0094141aa8672e7b477ab77ce_STOCKBASEDCOMPENSATIONPLANS"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/STOCKBASEDCOMPENSATIONPLANSTables" xlink:type="simple" xlink:href="prth-20200930.xsd#STOCKBASEDCOMPENSATIONPLANSTables"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/STOCKBASEDCOMPENSATIONPLANSTables" xlink:type="extended" id="i67efea978052403c9b46968009bf0b89_STOCKBASEDCOMPENSATIONPLANSTables"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/STOCKBASEDCOMPENSATIONPLANSSummaryofEquityBasedCompensationExpenseDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#STOCKBASEDCOMPENSATIONPLANSSummaryofEquityBasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/STOCKBASEDCOMPENSATIONPLANSSummaryofEquityBasedCompensationExpenseDetails" xlink:type="extended" id="idc3f2023764a4037b64990f6a3797985_STOCKBASEDCOMPENSATIONPLANSSummaryofEquityBasedCompensationExpenseDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5fcb56e1-ba18-4bfd-a7f1-e8fd52765291" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ShareBasedPaymentArrangementExpenseExcludingDeferredCompensationShareBasedArrangementsExpense_9d880f1d-9e2a-4e1b-b9c0-4488c36561c0" xlink:href="prth-20200930.xsd#prth_ShareBasedPaymentArrangementExpenseExcludingDeferredCompensationShareBasedArrangementsExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5fcb56e1-ba18-4bfd-a7f1-e8fd52765291" xlink:to="loc_prth_ShareBasedPaymentArrangementExpenseExcludingDeferredCompensationShareBasedArrangementsExpense_9d880f1d-9e2a-4e1b-b9c0-4488c36561c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_DeferredCompensationShareBasedArrangementsExpense_e363f969-951e-4b0a-86fa-d9ca9e551b56" xlink:href="prth-20200930.xsd#prth_DeferredCompensationShareBasedArrangementsExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5fcb56e1-ba18-4bfd-a7f1-e8fd52765291" xlink:to="loc_prth_DeferredCompensationShareBasedArrangementsExpense_e363f969-951e-4b0a-86fa-d9ca9e551b56" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_22a45bc1-7f78-4108-85d9-36b5a362ea90" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5fcb56e1-ba18-4bfd-a7f1-e8fd52765291" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_22a45bc1-7f78-4108-85d9-36b5a362ea90" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_79915c96-08b6-49ae-9095-aac9236086b6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_22a45bc1-7f78-4108-85d9-36b5a362ea90" xlink:to="loc_us-gaap_PlanNameAxis_79915c96-08b6-49ae-9095-aac9236086b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_79915c96-08b6-49ae-9095-aac9236086b6_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_79915c96-08b6-49ae-9095-aac9236086b6" xlink:to="loc_us-gaap_PlanNameDomain_79915c96-08b6-49ae-9095-aac9236086b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_1b5bbadd-972d-443a-ad40-9be7fdbadda4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_79915c96-08b6-49ae-9095-aac9236086b6" xlink:to="loc_us-gaap_PlanNameDomain_1b5bbadd-972d-443a-ad40-9be7fdbadda4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_A2018EquityIncentivePlanMember_b962cee0-93d5-4499-b4fd-312c9f0968ba" xlink:href="prth-20200930.xsd#prth_A2018EquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_1b5bbadd-972d-443a-ad40-9be7fdbadda4" xlink:to="loc_prth_A2018EquityIncentivePlanMember_b962cee0-93d5-4499-b4fd-312c9f0968ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_A2014ManagementIncentivePlanMember_9c52bba8-2a5a-45f8-b530-b9af12a53c26" xlink:href="prth-20200930.xsd#prth_A2014ManagementIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_1b5bbadd-972d-443a-ad40-9be7fdbadda4" xlink:to="loc_prth_A2014ManagementIncentivePlanMember_9c52bba8-2a5a-45f8-b530-b9af12a53c26" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/FAIRVALUE" xlink:type="simple" xlink:href="prth-20200930.xsd#FAIRVALUE"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/FAIRVALUE" xlink:type="extended" id="i7022395e5ced4e93a1fa27e57f6597f5_FAIRVALUE"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/FAIRVALUENarrativeDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#FAIRVALUENarrativeDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/FAIRVALUENarrativeDetails" xlink:type="extended" id="i5c6134e017814be4abeb24df9d1e25ba_FAIRVALUENarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bbba8ec1-0c4e-48ea-9fd8-678a0f57032d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_BusinessCombinationContingentConsiderationWeightedPayoutProbabilityPercentage_f5d38e55-363e-4b54-a15b-76e36a420ee5" xlink:href="prth-20200930.xsd#prth_BusinessCombinationContingentConsiderationWeightedPayoutProbabilityPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bbba8ec1-0c4e-48ea-9fd8-678a0f57032d" xlink:to="loc_prth_BusinessCombinationContingentConsiderationWeightedPayoutProbabilityPercentage_f5d38e55-363e-4b54-a15b-76e36a420ee5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_fedc78d6-823c-4fc8-bd24-2b7773541a2d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bbba8ec1-0c4e-48ea-9fd8-678a0f57032d" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_fedc78d6-823c-4fc8-bd24-2b7773541a2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_BusinessCombinationContingentConsiderationLiabilityFairValueDisclosure_1eedb214-b1b3-4848-a9de-1354af807702" xlink:href="prth-20200930.xsd#prth_BusinessCombinationContingentConsiderationLiabilityFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bbba8ec1-0c4e-48ea-9fd8-678a0f57032d" xlink:to="loc_prth_BusinessCombinationContingentConsiderationLiabilityFairValueDisclosure_1eedb214-b1b3-4848-a9de-1354af807702" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableFairValueDisclosure_69ac0798-a6c6-40c8-8029-86a5e197d415" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NotesReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bbba8ec1-0c4e-48ea-9fd8-678a0f57032d" xlink:to="loc_us-gaap_NotesReceivableFairValueDisclosure_69ac0798-a6c6-40c8-8029-86a5e197d415" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_d543028c-2808-49d4-9ef0-ecb65a320b5e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bbba8ec1-0c4e-48ea-9fd8-678a0f57032d" xlink:to="loc_us-gaap_LongTermDebtFairValue_d543028c-2808-49d4-9ef0-ecb65a320b5e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_4dfe90d1-c72a-4f89-862e-623c6d490f07" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bbba8ec1-0c4e-48ea-9fd8-678a0f57032d" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_4dfe90d1-c72a-4f89-862e-623c6d490f07" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8d560608-b5b3-4f1d-94e6-e4cd5b9a57b2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bbba8ec1-0c4e-48ea-9fd8-678a0f57032d" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8d560608-b5b3-4f1d-94e6-e4cd5b9a57b2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_7173c789-7510-4cb5-89de-09019b495b65" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8d560608-b5b3-4f1d-94e6-e4cd5b9a57b2" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_7173c789-7510-4cb5-89de-09019b495b65" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7173c789-7510-4cb5-89de-09019b495b65_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_7173c789-7510-4cb5-89de-09019b495b65" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7173c789-7510-4cb5-89de-09019b495b65_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_ed47da60-6d5b-4e35-bd17-523369f6d382" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_7173c789-7510-4cb5-89de-09019b495b65" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_ed47da60-6d5b-4e35-bd17-523369f6d382" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_e833087c-47dc-421c-aa56-c78a40699f57" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_ed47da60-6d5b-4e35-bd17-523369f6d382" xlink:to="loc_us-gaap_SeniorNotesMember_e833087c-47dc-421c-aa56-c78a40699f57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_c9ed22a7-df9a-4f65-a0c3-e786b704ab31" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8d560608-b5b3-4f1d-94e6-e4cd5b9a57b2" xlink:to="loc_us-gaap_DebtInstrumentAxis_c9ed22a7-df9a-4f65-a0c3-e786b704ab31" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_c9ed22a7-df9a-4f65-a0c3-e786b704ab31_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_c9ed22a7-df9a-4f65-a0c3-e786b704ab31" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_c9ed22a7-df9a-4f65-a0c3-e786b704ab31_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_1d11e902-1c53-4ecb-865c-14a6610c29f0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_c9ed22a7-df9a-4f65-a0c3-e786b704ab31" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_1d11e902-1c53-4ecb-865c-14a6610c29f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_SeniorTermLoanMaturingJanuary32023Member_a25b14c0-1950-4367-a5aa-5a2aa21b2b0f" xlink:href="prth-20200930.xsd#prth_SeniorTermLoanMaturingJanuary32023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1d11e902-1c53-4ecb-865c-14a6610c29f0" xlink:to="loc_prth_SeniorTermLoanMaturingJanuary32023Member_a25b14c0-1950-4367-a5aa-5a2aa21b2b0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_30b43252-62f5-4f4b-ac76-3181e1207b9e" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8d560608-b5b3-4f1d-94e6-e4cd5b9a57b2" xlink:to="loc_srt_RangeAxis_30b43252-62f5-4f4b-ac76-3181e1207b9e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_30b43252-62f5-4f4b-ac76-3181e1207b9e_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_30b43252-62f5-4f4b-ac76-3181e1207b9e" xlink:to="loc_srt_RangeMember_30b43252-62f5-4f4b-ac76-3181e1207b9e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_0cee01fd-79d2-4490-b58e-adb0aca76741" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_30b43252-62f5-4f4b-ac76-3181e1207b9e" xlink:to="loc_srt_RangeMember_0cee01fd-79d2-4490-b58e-adb0aca76741" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_4e0fb86a-b70f-4c49-ae38-a46e83464bfb" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0cee01fd-79d2-4490-b58e-adb0aca76741" xlink:to="loc_srt_MinimumMember_4e0fb86a-b70f-4c49-ae38-a46e83464bfb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_73eab7ee-3eee-4aed-8c42-8eb83e692d7c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0cee01fd-79d2-4490-b58e-adb0aca76741" xlink:to="loc_srt_MaximumMember_73eab7ee-3eee-4aed-8c42-8eb83e692d7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0ef6a82d-7bc7-4863-a4b1-9f2745f6dcf2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8d560608-b5b3-4f1d-94e6-e4cd5b9a57b2" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0ef6a82d-7bc7-4863-a4b1-9f2745f6dcf2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0ef6a82d-7bc7-4863-a4b1-9f2745f6dcf2_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0ef6a82d-7bc7-4863-a4b1-9f2745f6dcf2" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0ef6a82d-7bc7-4863-a4b1-9f2745f6dcf2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1b625840-d0c0-4c98-84ff-8a1326af3014" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0ef6a82d-7bc7-4863-a4b1-9f2745f6dcf2" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1b625840-d0c0-4c98-84ff-8a1326af3014" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_d21ba66e-68db-4e1b-9446-34859d4f159b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1b625840-d0c0-4c98-84ff-8a1326af3014" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_d21ba66e-68db-4e1b-9446-34859d4f159b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_4afb8e94-6d39-4bcc-97b2-061499ccc55a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8d560608-b5b3-4f1d-94e6-e4cd5b9a57b2" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_4afb8e94-6d39-4bcc-97b2-061499ccc55a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4afb8e94-6d39-4bcc-97b2-061499ccc55a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_4afb8e94-6d39-4bcc-97b2-061499ccc55a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4afb8e94-6d39-4bcc-97b2-061499ccc55a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_08ba71de-874a-4dfc-987b-59add2da4fb8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_4afb8e94-6d39-4bcc-97b2-061499ccc55a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_08ba71de-874a-4dfc-987b-59add2da4fb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PriorityPaymentSystemsTechPartnerMember_206ee5fe-8b8c-43eb-8023-5e4a40f3636b" xlink:href="prth-20200930.xsd#prth_PriorityPaymentSystemsTechPartnerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_08ba71de-874a-4dfc-987b-59add2da4fb8" xlink:to="loc_prth_PriorityPaymentSystemsTechPartnerMember_206ee5fe-8b8c-43eb-8023-5e4a40f3636b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PriorityPaymentSystemsNortheastMember_fca87133-48d2-4cbe-8f01-bf367f5a8bcc" xlink:href="prth-20200930.xsd#prth_PriorityPaymentSystemsNortheastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_08ba71de-874a-4dfc-987b-59add2da4fb8" xlink:to="loc_prth_PriorityPaymentSystemsNortheastMember_fca87133-48d2-4cbe-8f01-bf367f5a8bcc" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/SEGMENTINFORMATION" xlink:type="simple" xlink:href="prth-20200930.xsd#SEGMENTINFORMATION"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SEGMENTINFORMATION" xlink:type="extended" id="i0f96dc354cd047e6b24752a93620381a_SEGMENTINFORMATION"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/SEGMENTINFORMATIONTables" xlink:type="simple" xlink:href="prth-20200930.xsd#SEGMENTINFORMATIONTables"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SEGMENTINFORMATIONTables" xlink:type="extended" id="ie7c70c8be0cc40719e4cbd21ad260c41_SEGMENTINFORMATIONTables"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/SEGMENTINFORMATIONNarrativeDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#SEGMENTINFORMATIONNarrativeDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SEGMENTINFORMATIONNarrativeDetails" xlink:type="extended" id="i76d3b9c93354429e92099537e46ad5db_SEGMENTINFORMATIONNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_af502b26-83b0-49d7-9564-9b58b7c59534" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_f8a42c34-5aff-4d86-8c5a-2952920abe44" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af502b26-83b0-49d7-9564-9b58b7c59534" xlink:to="loc_us-gaap_NumberOfReportableSegments_f8a42c34-5aff-4d86-8c5a-2952920abe44" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_PercentageofRevenue_3566b56b-c4cc-4687-826e-b44d862475cb" xlink:href="prth-20200930.xsd#prth_PercentageofRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af502b26-83b0-49d7-9564-9b58b7c59534" xlink:to="loc_prth_PercentageofRevenue_3566b56b-c4cc-4687-826e-b44d862475cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_b9120c2a-24bf-4369-b8b8-f45841204f37" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af502b26-83b0-49d7-9564-9b58b7c59534" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_b9120c2a-24bf-4369-b8b8-f45841204f37" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_9c2bc2c0-4ee2-4cbc-91cb-aa789cfbd6b8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_b9120c2a-24bf-4369-b8b8-f45841204f37" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_9c2bc2c0-4ee2-4cbc-91cb-aa789cfbd6b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_9c2bc2c0-4ee2-4cbc-91cb-aa789cfbd6b8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_9c2bc2c0-4ee2-4cbc-91cb-aa789cfbd6b8" xlink:to="loc_us-gaap_SegmentDomain_9c2bc2c0-4ee2-4cbc-91cb-aa789cfbd6b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_a23188f3-939a-472b-948e-93e76d2759c9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_9c2bc2c0-4ee2-4cbc-91cb-aa789cfbd6b8" xlink:to="loc_us-gaap_SegmentDomain_a23188f3-939a-472b-948e-93e76d2759c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_CommercialPaymentsAndManagedServicesMember_2459d439-89a0-4c08-b752-d615a3bb4588" xlink:href="prth-20200930.xsd#prth_CommercialPaymentsAndManagedServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a23188f3-939a-472b-948e-93e76d2759c9" xlink:to="loc_prth_CommercialPaymentsAndManagedServicesMember_2459d439-89a0-4c08-b752-d615a3bb4588" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ConsumerPaymentsMember_4e665671-c7e1-4691-8957-e8e2401a064e" xlink:href="prth-20200930.xsd#prth_ConsumerPaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a23188f3-939a-472b-948e-93e76d2759c9" xlink:to="loc_prth_ConsumerPaymentsMember_4e665671-c7e1-4691-8957-e8e2401a064e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/SEGMENTINFORMATIONScheduleofSegmentReportingInformationbySegmentDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#SEGMENTINFORMATIONScheduleofSegmentReportingInformationbySegmentDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SEGMENTINFORMATIONScheduleofSegmentReportingInformationbySegmentDetails" xlink:type="extended" id="i32b8e848ef9c42e6b19e5fb253eb97dd_SEGMENTINFORMATIONScheduleofSegmentReportingInformationbySegmentDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_b04bd454-bfa4-4ad7-ba78-7bccc9a27e78" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_7da6899c-4f87-4ec3-862f-7db040e0976a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b04bd454-bfa4-4ad7-ba78-7bccc9a27e78" xlink:to="loc_us-gaap_RevenuesAbstract_7da6899c-4f87-4ec3-862f-7db040e0976a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_7b40b145-16f8-40bd-97a4-ab9551912be0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_7da6899c-4f87-4ec3-862f-7db040e0976a" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_7b40b145-16f8-40bd-97a4-ab9551912be0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAbstract_dae137bc-24d1-46fb-be2f-c4b5404fc234" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b04bd454-bfa4-4ad7-ba78-7bccc9a27e78" xlink:to="loc_us-gaap_NetIncomeLossAbstract_dae137bc-24d1-46fb-be2f-c4b5404fc234" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_52635521-9723-445c-83f1-1a9b9cead90d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_dae137bc-24d1-46fb-be2f-c4b5404fc234" xlink:to="loc_us-gaap_OperatingIncomeLoss_52635521-9723-445c-83f1-1a9b9cead90d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAmortizationAndAccretionNetAbstract_614e0d73-3a5f-477b-af10-460dd470eb4f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DepreciationAmortizationAndAccretionNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b04bd454-bfa4-4ad7-ba78-7bccc9a27e78" xlink:to="loc_us-gaap_DepreciationAmortizationAndAccretionNetAbstract_614e0d73-3a5f-477b-af10-460dd470eb4f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAndAmortization_2bd29315-2614-44c1-86b4-499f0609c184" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DepreciationAmortizationAndAccretionNetAbstract_614e0d73-3a5f-477b-af10-460dd470eb4f" xlink:to="loc_us-gaap_DepreciationAndAmortization_2bd29315-2614-44c1-86b4-499f0609c184" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_435cd190-e7fb-440f-8874-56441c1576c1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b04bd454-bfa4-4ad7-ba78-7bccc9a27e78" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_435cd190-e7fb-440f-8874-56441c1576c1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_8db13516-a8c9-46ab-b1e0-bef5083e833e" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_435cd190-e7fb-440f-8874-56441c1576c1" xlink:to="loc_srt_ConsolidationItemsAxis_8db13516-a8c9-46ab-b1e0-bef5083e833e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_8db13516-a8c9-46ab-b1e0-bef5083e833e_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_8db13516-a8c9-46ab-b1e0-bef5083e833e" xlink:to="loc_srt_ConsolidationItemsDomain_8db13516-a8c9-46ab-b1e0-bef5083e833e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_ffb6da3f-6cca-4746-9f14-b0a29b84438e" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_8db13516-a8c9-46ab-b1e0-bef5083e833e" xlink:to="loc_srt_ConsolidationItemsDomain_ffb6da3f-6cca-4746-9f14-b0a29b84438e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_5225c52f-280c-49c4-8e6c-03ca5177f665" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_ffb6da3f-6cca-4746-9f14-b0a29b84438e" xlink:to="loc_us-gaap_OperatingSegmentsMember_5225c52f-280c-49c4-8e6c-03ca5177f665" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_ede9a249-8e57-4a1a-a597-95dd67cab804" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_ffb6da3f-6cca-4746-9f14-b0a29b84438e" xlink:to="loc_us-gaap_CorporateNonSegmentMember_ede9a249-8e57-4a1a-a597-95dd67cab804" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_85db0f05-e9bc-4b9a-a0ad-9e955e4b4406" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_435cd190-e7fb-440f-8874-56441c1576c1" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_85db0f05-e9bc-4b9a-a0ad-9e955e4b4406" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_85db0f05-e9bc-4b9a-a0ad-9e955e4b4406_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_85db0f05-e9bc-4b9a-a0ad-9e955e4b4406" xlink:to="loc_us-gaap_SegmentDomain_85db0f05-e9bc-4b9a-a0ad-9e955e4b4406_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_6b6e21b6-2188-495c-b88c-b29ac9c41806" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_85db0f05-e9bc-4b9a-a0ad-9e955e4b4406" xlink:to="loc_us-gaap_SegmentDomain_6b6e21b6-2188-495c-b88c-b29ac9c41806" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_ConsumerPaymentsMember_b393590b-033d-4c27-9e02-3b74722af139" xlink:href="prth-20200930.xsd#prth_ConsumerPaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6b6e21b6-2188-495c-b88c-b29ac9c41806" xlink:to="loc_prth_ConsumerPaymentsMember_b393590b-033d-4c27-9e02-3b74722af139" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_CommercialPaymentsAndManagedServicesMember_908460c9-3920-47ba-94ef-6924ab6726a1" xlink:href="prth-20200930.xsd#prth_CommercialPaymentsAndManagedServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6b6e21b6-2188-495c-b88c-b29ac9c41806" xlink:to="loc_prth_CommercialPaymentsAndManagedServicesMember_908460c9-3920-47ba-94ef-6924ab6726a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_IntegratedPartnersMember_3a8b7c41-c58e-4342-ab40-1294e87ad0e6" xlink:href="prth-20200930.xsd#prth_IntegratedPartnersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6b6e21b6-2188-495c-b88c-b29ac9c41806" xlink:to="loc_prth_IntegratedPartnersMember_3a8b7c41-c58e-4342-ab40-1294e87ad0e6" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/SEGMENTINFORMATIONScheduleofReconciliationofTotalOperatingIncomeDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#SEGMENTINFORMATIONScheduleofReconciliationofTotalOperatingIncomeDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SEGMENTINFORMATIONScheduleofReconciliationofTotalOperatingIncomeDetails" xlink:type="extended" id="ia10a444079814c8b939bea9a68fd0497_SEGMENTINFORMATIONScheduleofReconciliationofTotalOperatingIncomeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_f0d4765f-de16-4f94-94d3-a2e4161631f3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_32bd5c77-2b0f-49cf-b718-1efa9d9f07ce" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f0d4765f-de16-4f94-94d3-a2e4161631f3" xlink:to="loc_us-gaap_OperatingIncomeLoss_32bd5c77-2b0f-49cf-b718-1efa9d9f07ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_219063b3-0ae0-432c-a731-7914220dad7d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f0d4765f-de16-4f94-94d3-a2e4161631f3" xlink:to="loc_us-gaap_InterestExpense_219063b3-0ae0-432c-a731-7914220dad7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_GainLossOnRestructuringAndModificationOfDebt_ef493680-f119-4511-983b-17fccf89eb9d" xlink:href="prth-20200930.xsd#prth_GainLossOnRestructuringAndModificationOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f0d4765f-de16-4f94-94d3-a2e4161631f3" xlink:to="loc_prth_GainLossOnRestructuringAndModificationOfDebt_ef493680-f119-4511-983b-17fccf89eb9d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_fd5badb4-2174-4e33-a4df-87008035c052" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainLossOnSaleOfBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f0d4765f-de16-4f94-94d3-a2e4161631f3" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_fd5badb4-2174-4e33-a4df-87008035c052" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_6f8f6e3a-2461-41a0-b057-5d5432b46ad1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f0d4765f-de16-4f94-94d3-a2e4161631f3" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_6f8f6e3a-2461-41a0-b057-5d5432b46ad1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_da4f36b4-f5ee-49e1-b25e-c8ba3b9ec290" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f0d4765f-de16-4f94-94d3-a2e4161631f3" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_da4f36b4-f5ee-49e1-b25e-c8ba3b9ec290" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_0cf0ed73-1736-4f9b-9ed5-bf0aefad58cd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f0d4765f-de16-4f94-94d3-a2e4161631f3" xlink:to="loc_us-gaap_ProfitLoss_0cf0ed73-1736-4f9b-9ed5-bf0aefad58cd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_92d87349-13b1-4f78-bfb8-f790c36b331f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f0d4765f-de16-4f94-94d3-a2e4161631f3" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_92d87349-13b1-4f78-bfb8-f790c36b331f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_f6079245-87dc-45e8-91aa-d8d0b18e4833" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f0d4765f-de16-4f94-94d3-a2e4161631f3" xlink:to="loc_us-gaap_NetIncomeLoss_f6079245-87dc-45e8-91aa-d8d0b18e4833" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_815efa66-10ff-4eba-b604-b970bfcfe32c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f0d4765f-de16-4f94-94d3-a2e4161631f3" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_815efa66-10ff-4eba-b604-b970bfcfe32c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_25a768a1-c89e-433c-80a7-e3d83e9f6194" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_815efa66-10ff-4eba-b604-b970bfcfe32c" xlink:to="loc_srt_ConsolidationItemsAxis_25a768a1-c89e-433c-80a7-e3d83e9f6194" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_25a768a1-c89e-433c-80a7-e3d83e9f6194_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_25a768a1-c89e-433c-80a7-e3d83e9f6194" xlink:to="loc_srt_ConsolidationItemsDomain_25a768a1-c89e-433c-80a7-e3d83e9f6194_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_a87271d6-3732-4a0a-b54c-ff576576aba6" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_25a768a1-c89e-433c-80a7-e3d83e9f6194" xlink:to="loc_srt_ConsolidationItemsDomain_a87271d6-3732-4a0a-b54c-ff576576aba6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_1e9a47b3-c763-437b-8f41-0824aad396d2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_a87271d6-3732-4a0a-b54c-ff576576aba6" xlink:to="loc_us-gaap_OperatingSegmentsMember_1e9a47b3-c763-437b-8f41-0824aad396d2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_2143ebd4-7d4d-4901-ae5a-b9def816a96e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_a87271d6-3732-4a0a-b54c-ff576576aba6" xlink:to="loc_us-gaap_CorporateNonSegmentMember_2143ebd4-7d4d-4901-ae5a-b9def816a96e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://miacquisitions.com/role/INCOMELOSSPERCOMMONSHARE" xlink:type="simple" xlink:href="prth-20200930.xsd#INCOMELOSSPERCOMMONSHARE"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/INCOMELOSSPERCOMMONSHARE" xlink:type="extended" id="i7172893b1e6742079f7e8cc180b005bf_INCOMELOSSPERCOMMONSHARE"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/INCOMELOSSPERCOMMONSHARETables" xlink:type="simple" xlink:href="prth-20200930.xsd#INCOMELOSSPERCOMMONSHARETables"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/INCOMELOSSPERCOMMONSHARETables" xlink:type="extended" id="if4c9f0b5f7934d13ac214c530943d640_INCOMELOSSPERCOMMONSHARETables"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/INCOMELOSSPERCOMMONSHAREScheduleofEarningsPerShareDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#INCOMELOSSPERCOMMONSHAREScheduleofEarningsPerShareDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/INCOMELOSSPERCOMMONSHAREScheduleofEarningsPerShareDetails" xlink:type="extended" id="i56370f16b1e3462ab72ea0cd5606eb3d_INCOMELOSSPERCOMMONSHAREScheduleofEarningsPerShareDetails"/>
  <link:roleRef roleURI="http://miacquisitions.com/role/INCOMELOSSPERCOMMONSHAREScheduleofAntidilutiveSecuritiesDetails" xlink:type="simple" xlink:href="prth-20200930.xsd#INCOMELOSSPERCOMMONSHAREScheduleofAntidilutiveSecuritiesDetails"/>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/INCOMELOSSPERCOMMONSHAREScheduleofAntidilutiveSecuritiesDetails" xlink:type="extended" id="i061ca59bc03d4200a1a7ff119facbbee_INCOMELOSSPERCOMMONSHAREScheduleofAntidilutiveSecuritiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_91174d4a-038d-4ca0-b4d6-7328c5fdb32d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_7012182d-2942-4567-868c-fb2493374cee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_91174d4a-038d-4ca0-b4d6-7328c5fdb32d" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_7012182d-2942-4567-868c-fb2493374cee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_a4a5efe0-38b6-406c-b4c6-2f609d58ccd2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_91174d4a-038d-4ca0-b4d6-7328c5fdb32d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_a4a5efe0-38b6-406c-b4c6-2f609d58ccd2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_52c406dd-09fe-43ee-8977-83928b419d49" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_91174d4a-038d-4ca0-b4d6-7328c5fdb32d" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_52c406dd-09fe-43ee-8977-83928b419d49" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_5f20ab95-f4e2-4fa6-ae7a-914c1746b225" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_52c406dd-09fe-43ee-8977-83928b419d49" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_5f20ab95-f4e2-4fa6-ae7a-914c1746b225" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_5f20ab95-f4e2-4fa6-ae7a-914c1746b225_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_5f20ab95-f4e2-4fa6-ae7a-914c1746b225" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_5f20ab95-f4e2-4fa6-ae7a-914c1746b225_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ac270366-7a1e-45e4-9652-363934b176de" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_5f20ab95-f4e2-4fa6-ae7a-914c1746b225" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ac270366-7a1e-45e4-9652-363934b176de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_879da9c4-2fc5-40de-913e-f55b33c10d64" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ac270366-7a1e-45e4-9652-363934b176de" xlink:to="loc_us-gaap_WarrantMember_879da9c4-2fc5-40de-913e-f55b33c10d64" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_OptionsAndWarrantsIssuedToAdvisorMember_b0604b40-fb25-4bcb-a329-7e7e6086074e" xlink:href="prth-20200930.xsd#prth_OptionsAndWarrantsIssuedToAdvisorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ac270366-7a1e-45e4-9652-363934b176de" xlink:to="loc_prth_OptionsAndWarrantsIssuedToAdvisorMember_b0604b40-fb25-4bcb-a329-7e7e6086074e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_4b3d4d79-04f1-4cd9-b270-82fb14e3d403" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ac270366-7a1e-45e4-9652-363934b176de" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_4b3d4d79-04f1-4cd9-b270-82fb14e3d403" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_ca61047c-14aa-4665-a7c8-4971b3ca7ce5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ac270366-7a1e-45e4-9652-363934b176de" xlink:to="loc_us-gaap_EmployeeStockOptionMember_ca61047c-14aa-4665-a7c8-4971b3ca7ce5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_LiabilityBasedRestrictedStockUnitMember_2f69037b-e45a-4000-97b1-ffb360f30646" xlink:href="prth-20200930.xsd#prth_LiabilityBasedRestrictedStockUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ac270366-7a1e-45e4-9652-363934b176de" xlink:to="loc_prth_LiabilityBasedRestrictedStockUnitMember_2f69037b-e45a-4000-97b1-ffb360f30646" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_EarnoutIncentiveAwardsMember_f0fff9a9-da75-4457-a00b-9327b1c9bf2a" xlink:href="prth-20200930.xsd#prth_EarnoutIncentiveAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ac270366-7a1e-45e4-9652-363934b176de" xlink:to="loc_prth_EarnoutIncentiveAwardsMember_f0fff9a9-da75-4457-a00b-9327b1c9bf2a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_RestrictedStockUnitsRSUsEquityIncentivePlanMember_d06bae0b-200e-4015-90ac-bfb2b3f30850" xlink:href="prth-20200930.xsd#prth_RestrictedStockUnitsRSUsEquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ac270366-7a1e-45e4-9652-363934b176de" xlink:to="loc_prth_RestrictedStockUnitsRSUsEquityIncentivePlanMember_d06bae0b-200e-4015-90ac-bfb2b3f30850" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_6d5d323d-845a-4981-9a28-4449f69adc38" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_52c406dd-09fe-43ee-8977-83928b419d49" xlink:to="loc_us-gaap_PlanNameAxis_6d5d323d-845a-4981-9a28-4449f69adc38" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_6d5d323d-845a-4981-9a28-4449f69adc38_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_6d5d323d-845a-4981-9a28-4449f69adc38" xlink:to="loc_us-gaap_PlanNameDomain_6d5d323d-845a-4981-9a28-4449f69adc38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_41e6b15f-d5c0-4c5c-be32-f275986c161e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_6d5d323d-845a-4981-9a28-4449f69adc38" xlink:to="loc_us-gaap_PlanNameDomain_41e6b15f-d5c0-4c5c-be32-f275986c161e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_prth_EarnoutIncentivePlanMember_e226b1ae-5c3c-4563-b95f-ad2ec2ac6e3c" xlink:href="prth-20200930.xsd#prth_EarnoutIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_41e6b15f-d5c0-4c5c-be32-f275986c161e" xlink:to="loc_prth_EarnoutIncentivePlanMember_e226b1ae-5c3c-4563-b95f-ad2ec2ac6e3c" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
