<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://miacquisitions.com/role/AccountsPayableAndAccruedExpenses" xlink:href="prth-20190930.xsd#AccountsPayableAndAccruedExpenses" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/AccountsPayableAndAccruedExpensesScheduleOfAccountsPayableAndAccruedExpensesDetails" xlink:href="prth-20190930.xsd#AccountsPayableAndAccruedExpensesScheduleOfAccountsPayableAndAccruedExpensesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/AccountsPayableAndAccruedExpensesTables" xlink:href="prth-20190930.xsd#AccountsPayableAndAccruedExpensesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/AcquisitionsAndContributionsOfAssets" xlink:href="prth-20190930.xsd#AcquisitionsAndContributionsOfAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/AcquisitionsAndContributionsOfAssetsEtabAndCumulusRelatedPartyDetails" xlink:href="prth-20190930.xsd#AcquisitionsAndContributionsOfAssetsEtabAndCumulusRelatedPartyDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/AcquisitionsAndContributionsOfAssetsResidualPortfolioAcquisitionDetails" xlink:href="prth-20190930.xsd#AcquisitionsAndContributionsOfAssetsResidualPortfolioAcquisitionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/AcquisitionsAndContributionsOfAssetsYapstoneDetails" xlink:href="prth-20190930.xsd#AcquisitionsAndContributionsOfAssetsYapstoneDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/CommitmentsAndContingencies" xlink:href="prth-20190930.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/CommitmentsAndContingenciesNarrativeDetails" xlink:href="prth-20190930.xsd#CommitmentsAndContingenciesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/CondensedConsolidatedBalanceSheets" xlink:href="prth-20190930.xsd#CondensedConsolidatedBalanceSheets" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:href="prth-20190930.xsd#CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/CondensedConsolidatedStatementsOfCashFlows" xlink:href="prth-20190930.xsd#CondensedConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/CondensedConsolidatedStatementsOfOperations" xlink:href="prth-20190930.xsd#CondensedConsolidatedStatementsOfOperations" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/Cover" xlink:href="prth-20190930.xsd#Cover" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/Equity" xlink:href="prth-20190930.xsd#Equity" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/EquityBasedCompensationPlans" xlink:href="prth-20190930.xsd#EquityBasedCompensationPlans" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/EquityBasedCompensationPlansSummaryOfEquityBasedCompensationExpenseDetails" xlink:href="prth-20190930.xsd#EquityBasedCompensationPlansSummaryOfEquityBasedCompensationExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/EquityBasedCompensationPlansTables" xlink:href="prth-20190930.xsd#EquityBasedCompensationPlansTables" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/EquityNarrativeDetails" xlink:href="prth-20190930.xsd#EquityNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/FairValue" xlink:href="prth-20190930.xsd#FairValue" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/FairValueNarrativeDetails" xlink:href="prth-20190930.xsd#FairValueNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/FairValueRollforwardDetails" xlink:href="prth-20190930.xsd#FairValueRollforwardDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/FairValueTables" xlink:href="prth-20190930.xsd#FairValueTables" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/GoodwillAndIntangibleAssets" xlink:href="prth-20190930.xsd#GoodwillAndIntangibleAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/GoodwillAndIntangibleAssetsGoodwillAllocationDetails" xlink:href="prth-20190930.xsd#GoodwillAndIntangibleAssetsGoodwillAllocationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/GoodwillAndIntangibleAssetsIntangibleAssetsDetails" xlink:href="prth-20190930.xsd#GoodwillAndIntangibleAssetsIntangibleAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/GoodwillAndIntangibleAssetsNarrativeDetails" xlink:href="prth-20190930.xsd#GoodwillAndIntangibleAssetsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/GoodwillAndIntangibleAssetsTables" xlink:href="prth-20190930.xsd#GoodwillAndIntangibleAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/IncomeTaxes" xlink:href="prth-20190930.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/IncomeTaxesNarrativeDetails" xlink:href="prth-20190930.xsd#IncomeTaxesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/IncomeTaxesScheduleOfIncomeTaxBenefitProvisionDetails" xlink:href="prth-20190930.xsd#IncomeTaxesScheduleOfIncomeTaxBenefitProvisionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/IncomeTaxesTables" xlink:href="prth-20190930.xsd#IncomeTaxesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/LongTermDebt" xlink:href="prth-20190930.xsd#LongTermDebt" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/LongTermDebtNarrativeDetails" xlink:href="prth-20190930.xsd#LongTermDebtNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/LongTermDebtRollingMaturitiesOfLongTermDebtDetails" xlink:href="prth-20190930.xsd#LongTermDebtRollingMaturitiesOfLongTermDebtDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/LongTermDebtScheduleOfLongTermDebtDetails" xlink:href="prth-20190930.xsd#LongTermDebtScheduleOfLongTermDebtDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/LongTermDebtTables" xlink:href="prth-20190930.xsd#LongTermDebtTables" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/LossPerShare" xlink:href="prth-20190930.xsd#LossPerShare" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/LossPerShareScheduleOfAntidilutiveSecuritiesDetails" xlink:href="prth-20190930.xsd#LossPerShareScheduleOfAntidilutiveSecuritiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/LossPerShareScheduleOfEarningsPerShareDetails" xlink:href="prth-20190930.xsd#LossPerShareScheduleOfEarningsPerShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/LossPerShareTables" xlink:href="prth-20190930.xsd#LossPerShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/NatureOfBusinessAndBasisOfPresentation" xlink:href="prth-20190930.xsd#NatureOfBusinessAndBasisOfPresentation" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/NatureOfBusinessAndBasisOfPresentationNarrativeDetails" xlink:href="prth-20190930.xsd#NatureOfBusinessAndBasisOfPresentationNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/NatureOfBusinessAndBasisOfPresentationPolicies" xlink:href="prth-20190930.xsd#NatureOfBusinessAndBasisOfPresentationPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/PropertyEquipmentAndSoftware" xlink:href="prth-20190930.xsd#PropertyEquipmentAndSoftware" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/PropertyEquipmentAndSoftwareNarrativeAndScheduleOfPropertyEquipmentAndSoftwareDetails" xlink:href="prth-20190930.xsd#PropertyEquipmentAndSoftwareNarrativeAndScheduleOfPropertyEquipmentAndSoftwareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/PropertyEquipmentAndSoftwareTables" xlink:href="prth-20190930.xsd#PropertyEquipmentAndSoftwareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/ReconciliationOfStockholdersEquityDeficitAndNonControllingInterest" xlink:href="prth-20190930.xsd#ReconciliationOfStockholdersEquityDeficitAndNonControllingInterest" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/ReconciliationOfStockholdersEquityDeficitAndNonControllingInterestEquityReconciliationDetails" xlink:href="prth-20190930.xsd#ReconciliationOfStockholdersEquityDeficitAndNonControllingInterestEquityReconciliationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/ReconciliationOfStockholdersEquityDeficitAndNonControllingInterestNarrativeDetails" xlink:href="prth-20190930.xsd#ReconciliationOfStockholdersEquityDeficitAndNonControllingInterestNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/ReconciliationOfStockholdersEquityDeficitAndNonControllingInterestTables" xlink:href="prth-20190930.xsd#ReconciliationOfStockholdersEquityDeficitAndNonControllingInterestTables" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/RelatedPartyAndOtherTransactions" xlink:href="prth-20190930.xsd#RelatedPartyAndOtherTransactions" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/RelatedPartyAndOtherTransactionsNarrativeDetails" xlink:href="prth-20190930.xsd#RelatedPartyAndOtherTransactionsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/SegmentInformation" xlink:href="prth-20190930.xsd#SegmentInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/SegmentInformationNarrativeDetails" xlink:href="prth-20190930.xsd#SegmentInformationNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/SegmentInformationReconciliationOfTotalOperatingIncomeDetails" xlink:href="prth-20190930.xsd#SegmentInformationReconciliationOfTotalOperatingIncomeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/SegmentInformationScheduleOfSegmentReportingInformationBySegmentDetails" xlink:href="prth-20190930.xsd#SegmentInformationScheduleOfSegmentReportingInformationBySegmentDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/SegmentInformationTables" xlink:href="prth-20190930.xsd#SegmentInformationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/SettlementAssetsAndObligations" xlink:href="prth-20190930.xsd#SettlementAssetsAndObligations" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/SettlementAssetsAndObligationsDetails" xlink:href="prth-20190930.xsd#SettlementAssetsAndObligationsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://miacquisitions.com/role/SettlementAssetsAndObligationsTables" xlink:href="prth-20190930.xsd#SettlementAssetsAndObligationsTables" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/AccountsPayableAndAccruedExpenses" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/AccountsPayableAndAccruedExpensesScheduleOfAccountsPayableAndAccruedExpensesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/AccountsPayableAndAccruedExpensesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/AcquisitionsAndContributionsOfAssets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/AcquisitionsAndContributionsOfAssetsEtabAndCumulusRelatedPartyDetails" xlink:type="extended">
    <link:loc xlink:href="prth-20190930.xsd#prth_ScheduleofAssetAcquisitionLineItems" xlink:label="loc_prth_ScheduleofAssetAcquisitionLineItems_D495A7CAD4D45BBF9A9D29DB9BB4AF3F" xlink:type="locator" />
    <link:loc xlink:href="prth-20190930.xsd#prth_ScheduleofAssetAcquisitionTable" xlink:label="loc_prth_ScheduleofAssetAcquisitionTable_B2197D34C5465B9A94B393FC87D6EEE7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_D495A7CAD4D45BBF9A9D29DB9BB4AF3F" xlink:to="loc_prth_ScheduleofAssetAcquisitionTable_B2197D34C5465B9A94B393FC87D6EEE7" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_BEA930D1E77E59AAB6E98BC2E59E5B07" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleofAssetAcquisitionTable_B2197D34C5465B9A94B393FC87D6EEE7" xlink:to="loc_us-gaap_TitleOfIndividualAxis_BEA930D1E77E59AAB6E98BC2E59E5B07" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_614C192BC07C883C890E77D4E77D3AD3_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TitleOfIndividualAxis_BEA930D1E77E59AAB6E98BC2E59E5B07" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_614C192BC07C883C890E77D4E77D3AD3_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_74E95AF971365FBABE275B8D2F68E267" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis_BEA930D1E77E59AAB6E98BC2E59E5B07" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_74E95AF971365FBABE275B8D2F68E267" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_PresidentChiefExecutiveOfficerAndChairmanMember" xlink:label="loc_prth_PresidentChiefExecutiveOfficerAndChairmanMember_1413E92E2D5C5A3584657092BD55F819" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_74E95AF971365FBABE275B8D2F68E267" xlink:to="loc_prth_PresidentChiefExecutiveOfficerAndChairmanMember_1413E92E2D5C5A3584657092BD55F819" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_PercentageOfOwnershipBeforeTransaction" xlink:label="loc_prth_PercentageOfOwnershipBeforeTransaction_B811B6097A44562C9D3EEB1C7643FBF5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_D495A7CAD4D45BBF9A9D29DB9BB4AF3F" xlink:to="loc_prth_PercentageOfOwnershipBeforeTransaction_B811B6097A44562C9D3EEB1C7643FBF5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RedeemableNoncontrollingInterestEquityPreferredRedemptionValue" xlink:label="loc_us-gaap_RedeemableNoncontrollingInterestEquityPreferredRedemptionValue_92F3A7B1F60B54FDAA8040AA8917A4D3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_D495A7CAD4D45BBF9A9D29DB9BB4AF3F" xlink:to="loc_us-gaap_RedeemableNoncontrollingInterestEquityPreferredRedemptionValue_92F3A7B1F60B54FDAA8040AA8917A4D3" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_RedeemableNoncontrollingInterestEquityPreferredAnnualPreferredYieldPercent" xlink:label="loc_prth_RedeemableNoncontrollingInterestEquityPreferredAnnualPreferredYieldPercent_9FC6A229D0A155DABB2458BB46F8826F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_D495A7CAD4D45BBF9A9D29DB9BB4AF3F" xlink:to="loc_prth_RedeemableNoncontrollingInterestEquityPreferredAnnualPreferredYieldPercent_9FC6A229D0A155DABB2458BB46F8826F" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_PreferredStockPercentageOwned" xlink:label="loc_prth_PreferredStockPercentageOwned_648C74103C45537488FEB35974FC5BED" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_D495A7CAD4D45BBF9A9D29DB9BB4AF3F" xlink:to="loc_prth_PreferredStockPercentageOwned_648C74103C45537488FEB35974FC5BED" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/AcquisitionsAndContributionsOfAssetsResidualPortfolioAcquisitionDetails" xlink:type="extended">
    <link:loc xlink:href="prth-20190930.xsd#prth_ScheduleofAssetAcquisitionLineItems" xlink:label="loc_prth_ScheduleofAssetAcquisitionLineItems_1705F72ABF53E7CF4D173CFEAF1DAAC9" xlink:type="locator" />
    <link:loc xlink:href="prth-20190930.xsd#prth_ScheduleofAssetAcquisitionTable" xlink:label="loc_prth_ScheduleofAssetAcquisitionTable_4F0D4BC1941AEE9453373CFEAF1A878A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_1705F72ABF53E7CF4D173CFEAF1DAAC9" xlink:to="loc_prth_ScheduleofAssetAcquisitionTable_4F0D4BC1941AEE9453373CFEAF1A878A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_54403DDB1959AB7BB7E23CFEAF1AD10E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleofAssetAcquisitionTable_4F0D4BC1941AEE9453373CFEAF1A878A" xlink:to="loc_us-gaap_StatementScenarioAxis_54403DDB1959AB7BB7E23CFEAF1AD10E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_1C8A4E7E90FA4D417B0D3CFEAF1A8B5C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_54403DDB1959AB7BB7E23CFEAF1AD10E" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_1C8A4E7E90FA4D417B0D3CFEAF1A8B5C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_1C8A4E7E90FA4D417B0D3CFEAF1A8B5C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_54403DDB1959AB7BB7E23CFEAF1AD10E" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_1C8A4E7E90FA4D417B0D3CFEAF1A8B5C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioForecastMember" xlink:label="loc_us-gaap_ScenarioForecastMember_508B3D800147C4AFDCBD3CFEAF1BFE9B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_1C8A4E7E90FA4D417B0D3CFEAF1A8B5C" xlink:to="loc_us-gaap_ScenarioForecastMember_508B3D800147C4AFDCBD3CFEAF1BFE9B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_C081B863AF76FF0D3A6D3CFEAF1B3B79" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleofAssetAcquisitionTable_4F0D4BC1941AEE9453373CFEAF1A878A" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_C081B863AF76FF0D3A6D3CFEAF1B3B79" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_A09769341845C9DA83DA3CFEAF1BB6F2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_C081B863AF76FF0D3A6D3CFEAF1B3B79" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_A09769341845C9DA83DA3CFEAF1BB6F2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_A09769341845C9DA83DA3CFEAF1BB6F2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_C081B863AF76FF0D3A6D3CFEAF1B3B79" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_A09769341845C9DA83DA3CFEAF1BB6F2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditMember" xlink:label="loc_us-gaap_LineOfCreditMember_97EECC5351DB930101AF3CFEAF1CCBEE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_A09769341845C9DA83DA3CFEAF1BB6F2" xlink:to="loc_us-gaap_LineOfCreditMember_97EECC5351DB930101AF3CFEAF1CCBEE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_EE7E83311050986D0ABB3CFEAF1C6FCA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleofAssetAcquisitionTable_4F0D4BC1941AEE9453373CFEAF1A878A" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_EE7E83311050986D0ABB3CFEAF1C6FCA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_B335EBB4F858380A70453CFEAF1C2BAE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_EE7E83311050986D0ABB3CFEAF1C6FCA" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_B335EBB4F858380A70453CFEAF1C2BAE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_B335EBB4F858380A70453CFEAF1C2BAE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_EE7E83311050986D0ABB3CFEAF1C6FCA" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_B335EBB4F858380A70453CFEAF1C2BAE" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_SyndicateOfLendersMember" xlink:label="loc_prth_SyndicateOfLendersMember_0CE51022282A49FFEEF53CFEAF1C540E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_B335EBB4F858380A70453CFEAF1C2BAE" xlink:to="loc_prth_SyndicateOfLendersMember_0CE51022282A49FFEEF53CFEAF1C540E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_EDC4D2570724F62C85F23CFEAF1DCC0D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleofAssetAcquisitionTable_4F0D4BC1941AEE9453373CFEAF1A878A" xlink:to="loc_us-gaap_CreditFacilityAxis_EDC4D2570724F62C85F23CFEAF1DCC0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_541677CE6966435DE0233CFEAF1DF651_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_EDC4D2570724F62C85F23CFEAF1DCC0D" xlink:to="loc_us-gaap_CreditFacilityDomain_541677CE6966435DE0233CFEAF1DF651_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_541677CE6966435DE0233CFEAF1DF651" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_EDC4D2570724F62C85F23CFEAF1DCC0D" xlink:to="loc_us-gaap_CreditFacilityDomain_541677CE6966435DE0233CFEAF1DF651" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_TermLoanMember" xlink:label="loc_prth_TermLoanMember_206B27FEF5FCA7A4DA6C3CFEAF1DA560" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_541677CE6966435DE0233CFEAF1DF651" xlink:to="loc_prth_TermLoanMember_206B27FEF5FCA7A4DA6C3CFEAF1DA560" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_BCD42043ABB9671DB54D3CFEAF1DC2F9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_541677CE6966435DE0233CFEAF1DF651" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_BCD42043ABB9671DB54D3CFEAF1DC2F9" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_AssetAcquisitionIntangibleAssets" xlink:label="loc_prth_AssetAcquisitionIntangibleAssets_342BDD6A31ED80AD88AD3CFEAF1D5B0C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_1705F72ABF53E7CF4D173CFEAF1DAAC9" xlink:to="loc_prth_AssetAcquisitionIntangibleAssets_342BDD6A31ED80AD88AD3CFEAF1D5B0C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_23734FB53E71DD6BFDED3CFEAF1E168E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_1705F72ABF53E7CF4D173CFEAF1DAAC9" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_23734FB53E71DD6BFDED3CFEAF1E168E" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_AssetAcquisitionContingentConsideration" xlink:label="loc_prth_AssetAcquisitionContingentConsideration_E56FF209CF448506DF563CFEAF1E06BB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_1705F72ABF53E7CF4D173CFEAF1DAAC9" xlink:to="loc_prth_AssetAcquisitionContingentConsideration_E56FF209CF448506DF563CFEAF1E06BB" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/AcquisitionsAndContributionsOfAssetsYapstoneDetails" xlink:type="extended">
    <link:loc xlink:href="prth-20190930.xsd#prth_ScheduleofAssetAcquisitionLineItems" xlink:label="loc_prth_ScheduleofAssetAcquisitionLineItems_A56D455B084E5F65ACF39D9274D238C7" xlink:type="locator" />
    <link:loc xlink:href="prth-20190930.xsd#prth_ScheduleofAssetAcquisitionTable" xlink:label="loc_prth_ScheduleofAssetAcquisitionTable_5885B54C025F504DA902873054440AE1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_A56D455B084E5F65ACF39D9274D238C7" xlink:to="loc_prth_ScheduleofAssetAcquisitionTable_5885B54C025F504DA902873054440AE1" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="prth-20190930.xsd#prth_AssetAcquisitionAxis" xlink:label="loc_prth_AssetAcquisitionAxis_A0BBCCD9252050BB975227A96C3D79DF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleofAssetAcquisitionTable_5885B54C025F504DA902873054440AE1" xlink:to="loc_prth_AssetAcquisitionAxis_A0BBCCD9252050BB975227A96C3D79DF" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_AssetAcquisitionDomain" xlink:label="loc_prth_AssetAcquisitionDomain_7A068458B28AC68708DB73F727C87946_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_prth_AssetAcquisitionAxis_A0BBCCD9252050BB975227A96C3D79DF" xlink:to="loc_prth_AssetAcquisitionDomain_7A068458B28AC68708DB73F727C87946_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_AssetAcquisitionDomain" xlink:label="loc_prth_AssetAcquisitionDomain_9D555A7D14445AD3988640D1F3E7C4F4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_prth_AssetAcquisitionAxis_A0BBCCD9252050BB975227A96C3D79DF" xlink:to="loc_prth_AssetAcquisitionDomain_9D555A7D14445AD3988640D1F3E7C4F4" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_YapStoneIncMember" xlink:label="loc_prth_YapStoneIncMember_5B6B18AC8B075F358A7455FAD41BF00D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_AssetAcquisitionDomain_9D555A7D14445AD3988640D1F3E7C4F4" xlink:to="loc_prth_YapStoneIncMember_5B6B18AC8B075F358A7455FAD41BF00D" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_PaymentsForAssetAcquisitions" xlink:label="loc_prth_PaymentsForAssetAcquisitions_86E7787A9A9753E8ABC2715DDB474975" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_A56D455B084E5F65ACF39D9274D238C7" xlink:to="loc_prth_PaymentsForAssetAcquisitions_86E7787A9A9753E8ABC2715DDB474975" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MinorityInterest" xlink:label="loc_us-gaap_MinorityInterest_28EDE4F28F3B5E52B77E23A61B8E83C9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_A56D455B084E5F65ACF39D9274D238C7" xlink:to="loc_us-gaap_MinorityInterest_28EDE4F28F3B5E52B77E23A61B8E83C9" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_AssetAcquisitionSoftwareLicenseAgreement" xlink:label="loc_prth_AssetAcquisitionSoftwareLicenseAgreement_3470859ADB4C5269BDB3C1FFC4C53D7B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_A56D455B084E5F65ACF39D9274D238C7" xlink:to="loc_prth_AssetAcquisitionSoftwareLicenseAgreement_3470859ADB4C5269BDB3C1FFC4C53D7B" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_AssetAcquisitionServiceAgreement" xlink:label="loc_prth_AssetAcquisitionServiceAgreement_1D9A407FAC645DFCB9B7D1D4F98A6630" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_A56D455B084E5F65ACF39D9274D238C7" xlink:to="loc_prth_AssetAcquisitionServiceAgreement_1D9A407FAC645DFCB9B7D1D4F98A6630" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/CommitmentsAndContingenciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="prth-20190930.xsd#prth_ScheduleofAssetAcquisitionLineItems" xlink:label="loc_prth_ScheduleofAssetAcquisitionLineItems_BA1962E0032D5D8EACD54657C14F4F4F" xlink:type="locator" />
    <link:loc xlink:href="prth-20190930.xsd#prth_ScheduleofAssetAcquisitionTable" xlink:label="loc_prth_ScheduleofAssetAcquisitionTable_C23F7385420157228797073C76E33621" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_BA1962E0032D5D8EACD54657C14F4F4F" xlink:to="loc_prth_ScheduleofAssetAcquisitionTable_C23F7385420157228797073C76E33621" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="prth-20190930.xsd#prth_AssetAcquisitionAxis" xlink:label="loc_prth_AssetAcquisitionAxis_DD5394788B2D529EB7144BE815556359" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleofAssetAcquisitionTable_C23F7385420157228797073C76E33621" xlink:to="loc_prth_AssetAcquisitionAxis_DD5394788B2D529EB7144BE815556359" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_AssetAcquisitionDomain" xlink:label="loc_prth_AssetAcquisitionDomain_BD34C4FCD40B5C924B058B3C3A33F86D_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_prth_AssetAcquisitionAxis_DD5394788B2D529EB7144BE815556359" xlink:to="loc_prth_AssetAcquisitionDomain_BD34C4FCD40B5C924B058B3C3A33F86D_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_AssetAcquisitionDomain" xlink:label="loc_prth_AssetAcquisitionDomain_7D196528B0E25AC0AAA5ED8F57FE3DE9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_prth_AssetAcquisitionAxis_DD5394788B2D529EB7144BE815556359" xlink:to="loc_prth_AssetAcquisitionDomain_7D196528B0E25AC0AAA5ED8F57FE3DE9" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_DirectConnectMerchantServicesLLCMember" xlink:label="loc_prth_DirectConnectMerchantServicesLLCMember_00E0B5FA915D5DBAA9798422BD7BBB8B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_AssetAcquisitionDomain_7D196528B0E25AC0AAA5ED8F57FE3DE9" xlink:to="loc_prth_DirectConnectMerchantServicesLLCMember_00E0B5FA915D5DBAA9798422BD7BBB8B" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_CertainMerchantPortfolioResidualRightsMember" xlink:label="loc_prth_CertainMerchantPortfolioResidualRightsMember_2B1968C9607E51C797448130D9AAD3E9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_AssetAcquisitionDomain_7D196528B0E25AC0AAA5ED8F57FE3DE9" xlink:to="loc_prth_CertainMerchantPortfolioResidualRightsMember_2B1968C9607E51C797448130D9AAD3E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_2676B5D6943359E6AC81EDF8E6B54358" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_prth_ScheduleofAssetAcquisitionTable_C23F7385420157228797073C76E33621" xlink:to="loc_us-gaap_StatementScenarioAxis_2676B5D6943359E6AC81EDF8E6B54358" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_9E9BE70510E9D3C4770F8B3C3A34CE44_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_2676B5D6943359E6AC81EDF8E6B54358" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_9E9BE70510E9D3C4770F8B3C3A34CE44_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_949C3FE28EC75E2A9E51E7CDED659313" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_2676B5D6943359E6AC81EDF8E6B54358" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_949C3FE28EC75E2A9E51E7CDED659313" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioForecastMember" xlink:label="loc_us-gaap_ScenarioForecastMember_46052080FB375D3A873A8C4CACC41611" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_949C3FE28EC75E2A9E51E7CDED659313" xlink:to="loc_us-gaap_ScenarioForecastMember_46052080FB375D3A873A8C4CACC41611" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_ContingentCashPaymentsForAssetAcquisitions" xlink:label="loc_prth_ContingentCashPaymentsForAssetAcquisitions_BA73DE695B8353B390C36F79B85486FE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ScheduleofAssetAcquisitionLineItems_BA1962E0032D5D8EACD54657C14F4F4F" xlink:to="loc_prth_ContingentCashPaymentsForAssetAcquisitions_BA73DE695B8353B390C36F79B85486FE" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/CondensedConsolidatedBalanceSheets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/CondensedConsolidatedStatementsOfCashFlows" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/CondensedConsolidatedStatementsOfOperations" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_43E94AC99F6FE934300C6020249AF3B7" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_ECDFE1E8AA7648655E44602024996CCA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_43E94AC99F6FE934300C6020249AF3B7" xlink:to="loc_us-gaap_StatementTable_ECDFE1E8AA7648655E44602024996CCA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis_9CCBA3D1DD390C66DD1460202499CCAE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_ECDFE1E8AA7648655E44602024996CCA" xlink:to="loc_srt_ProductOrServiceAxis_9CCBA3D1DD390C66DD1460202499CCAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_F3E2CC91CD8874FA215560202499C7A3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_9CCBA3D1DD390C66DD1460202499CCAE" xlink:to="loc_srt_ProductsAndServicesDomain_F3E2CC91CD8874FA215560202499C7A3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_F3E2CC91CD8874FA215560202499C7A3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_9CCBA3D1DD390C66DD1460202499CCAE" xlink:to="loc_srt_ProductsAndServicesDomain_F3E2CC91CD8874FA215560202499C7A3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditAndDebitCardMember" xlink:label="loc_us-gaap_CreditAndDebitCardMember_6D7B01603D0797563E9D6020249952DD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_F3E2CC91CD8874FA215560202499C7A3" xlink:to="loc_us-gaap_CreditAndDebitCardMember_6D7B01603D0797563E9D6020249952DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LicenseAndServiceMember" xlink:label="loc_us-gaap_LicenseAndServiceMember_A7E083F84FDDFAA8742B6020249A3663" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_F3E2CC91CD8874FA215560202499C7A3" xlink:to="loc_us-gaap_LicenseAndServiceMember_A7E083F84FDDFAA8742B6020249A3663" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenuesAbstract" xlink:label="loc_us-gaap_RevenuesAbstract_E2F1D7FD9B57100C984E6020249AE77B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_43E94AC99F6FE934300C6020249AF3B7" xlink:to="loc_us-gaap_RevenuesAbstract_E2F1D7FD9B57100C984E6020249AE77B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_F0143A8939EDC1DF36A260335447B217" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_E2F1D7FD9B57100C984E6020249AE77B" xlink:to="loc_us-gaap_Revenues_F0143A8939EDC1DF36A260335447B217" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingExpensesAbstract" xlink:label="loc_us-gaap_OperatingExpensesAbstract_203131EE4FD59B9D1D9C6020249B50FB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_43E94AC99F6FE934300C6020249AF3B7" xlink:to="loc_us-gaap_OperatingExpensesAbstract_203131EE4FD59B9D1D9C6020249B50FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_2475E5E7E4894AFF248B6020249BF5F8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_203131EE4FD59B9D1D9C6020249B50FB" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_2475E5E7E4894AFF248B6020249BF5F8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LaborAndRelatedExpense" xlink:label="loc_us-gaap_LaborAndRelatedExpense_DEE77ABE7769EB96E8886020249B38A8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_203131EE4FD59B9D1D9C6020249B50FB" xlink:to="loc_us-gaap_LaborAndRelatedExpense_DEE77ABE7769EB96E8886020249B38A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DepreciationAndAmortization" xlink:label="loc_us-gaap_DepreciationAndAmortization_CEDA1AD2E5DE6EB894CE6020249BFFDB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_203131EE4FD59B9D1D9C6020249B50FB" xlink:to="loc_us-gaap_DepreciationAndAmortization_CEDA1AD2E5DE6EB894CE6020249BFFDB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_38DB11A5994E1D162E346020249B98A9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_203131EE4FD59B9D1D9C6020249B50FB" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_38DB11A5994E1D162E346020249B98A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaap_OperatingExpenses_9A46811586159E7498D76020249C9134" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_203131EE4FD59B9D1D9C6020249B50FB" xlink:to="loc_us-gaap_OperatingExpenses_9A46811586159E7498D76020249C9134" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_F02296EF481156727AE96020249CDEDC" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_43E94AC99F6FE934300C6020249AF3B7" xlink:to="loc_us-gaap_OperatingIncomeLoss_F02296EF481156727AE96020249CDEDC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpenseAbstract" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_D7FC9A08BBED9072D36D6020249C3927" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_43E94AC99F6FE934300C6020249AF3B7" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_D7FC9A08BBED9072D36D6020249C3927" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_72B9704E457194499B346020249C8754" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_D7FC9A08BBED9072D36D6020249C3927" xlink:to="loc_us-gaap_InterestExpense_72B9704E457194499B346020249C8754" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_2C31D044B0EC459D7E6F6020249C029B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_D7FC9A08BBED9072D36D6020249C3927" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_2C31D044B0EC459D7E6F6020249C029B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_CAD69A59B65E3E5E3F3D6020249C60A2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_D7FC9A08BBED9072D36D6020249C3927" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_CAD69A59B65E3E5E3F3D6020249C60A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossAttributableToParent" xlink:label="loc_us-gaap_IncomeLossAttributableToParent_8828E5FD6C3F9E3F21C36020249D2893" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_43E94AC99F6FE934300C6020249AF3B7" xlink:to="loc_us-gaap_IncomeLossAttributableToParent_8828E5FD6C3F9E3F21C36020249D2893" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_0270068291D7F10C11196020249D0EB2" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_43E94AC99F6FE934300C6020249AF3B7" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_0270068291D7F10C11196020249D0EB2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_92E2798A9237BB37A9956020249DCE23" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_43E94AC99F6FE934300C6020249AF3B7" xlink:to="loc_us-gaap_NetIncomeLoss_92E2798A9237BB37A9956020249DCE23" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareBasicAndDilutedAbstract" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_89C4E092ACFA21163FD56020249D39A8" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_43E94AC99F6FE934300C6020249AF3B7" xlink:to="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_89C4E092ACFA21163FD56020249D39A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareBasicAndDiluted" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDiluted_30AFA6CBC92CE82C945F6020249D695C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_89C4E092ACFA21163FD56020249D39A8" xlink:to="loc_us-gaap_EarningsPerShareBasicAndDiluted_30AFA6CBC92CE82C945F6020249D695C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_A7D8C560126C76F8466D6020249E25B5" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_43E94AC99F6FE934300C6020249AF3B7" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_A7D8C560126C76F8466D6020249E25B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_2D5C469CD7BE6DC8E2376020249EDDC6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_A7D8C560126C76F8466D6020249E25B5" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_2D5C469CD7BE6DC8E2376020249EDDC6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_85CE0306587E926F1D5F6020249EB35E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_A7D8C560126C76F8466D6020249E25B5" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_85CE0306587E926F1D5F6020249EB35E" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_ChangeInTaxBasisAbstractAbstract" xlink:label="loc_prth_ChangeInTaxBasisAbstractAbstract_A895E3BA0CE196CBA29B6020249E5B75" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_43E94AC99F6FE934300C6020249AF3B7" xlink:to="loc_prth_ChangeInTaxBasisAbstractAbstract_A895E3BA0CE196CBA29B6020249E5B75" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_BusinessAcquisitionProFormaIncomeTaxExpenseBenefit" xlink:label="loc_prth_BusinessAcquisitionProFormaIncomeTaxExpenseBenefit_0D32DCBCCD8D89ABADD86020249EED77" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ChangeInTaxBasisAbstractAbstract_A895E3BA0CE196CBA29B6020249E5B75" xlink:to="loc_prth_BusinessAcquisitionProFormaIncomeTaxExpenseBenefit_0D32DCBCCD8D89ABADD86020249EED77" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_D097E6FC2160C143B85F6020249F3165" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ChangeInTaxBasisAbstractAbstract_A895E3BA0CE196CBA29B6020249E5B75" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_D097E6FC2160C143B85F6020249F3165" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareProFormaAbstract" xlink:label="loc_us-gaap_EarningsPerShareProFormaAbstract_E54A2FD6FCAD2AC0D3756020249F758D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_prth_ChangeInTaxBasisAbstractAbstract_A895E3BA0CE196CBA29B6020249E5B75" xlink:to="loc_us-gaap_EarningsPerShareProFormaAbstract_E54A2FD6FCAD2AC0D3756020249F758D" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_BusinessAcquisitionProFormaEarningsPerShareBasicAndDiluted" xlink:label="loc_prth_BusinessAcquisitionProFormaEarningsPerShareBasicAndDiluted_B3B0D2C891E71C4AFDC46020249F962E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareProFormaAbstract_E54A2FD6FCAD2AC0D3756020249F758D" xlink:to="loc_prth_BusinessAcquisitionProFormaEarningsPerShareBasicAndDiluted_B3B0D2C891E71C4AFDC46020249F962E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/Cover" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/Equity" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/EquityBasedCompensationPlans" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/EquityBasedCompensationPlansSummaryOfEquityBasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E379B92FE31BC5BC8D7B6020233107B4" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F6D74266F49F6110E6086020232A54E3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E379B92FE31BC5BC8D7B6020233107B4" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F6D74266F49F6110E6086020232A54E3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_EB15AA5D531F0BCBA7D06020232BDC18" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F6D74266F49F6110E6086020232A54E3" xlink:to="loc_us-gaap_PlanNameAxis_EB15AA5D531F0BCBA7D06020232BDC18" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_51ACF96F3AC80F5BD8D96020232B2BB9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_EB15AA5D531F0BCBA7D06020232BDC18" xlink:to="loc_us-gaap_PlanNameDomain_51ACF96F3AC80F5BD8D96020232B2BB9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_51ACF96F3AC80F5BD8D96020232B2BB9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_EB15AA5D531F0BCBA7D06020232BDC18" xlink:to="loc_us-gaap_PlanNameDomain_51ACF96F3AC80F5BD8D96020232B2BB9" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_A2018EquityIncentivePlanMember" xlink:label="loc_prth_A2018EquityIncentivePlanMember_2C5901F7DC60C475FF126020232B63EC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_51ACF96F3AC80F5BD8D96020232B2BB9" xlink:to="loc_prth_A2018EquityIncentivePlanMember_2C5901F7DC60C475FF126020232B63EC" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_A2014ManagementIncentivePlanMember" xlink:label="loc_prth_A2014ManagementIncentivePlanMember_F469221F122BB39BCAFC60202330DF3A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_51ACF96F3AC80F5BD8D96020232B2BB9" xlink:to="loc_prth_A2014ManagementIncentivePlanMember_F469221F122BB39BCAFC60202330DF3A" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_TheEarnoutIncentivePlanMember" xlink:label="loc_prth_TheEarnoutIncentivePlanMember_47F8F82056005EF21654602023318007" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_51ACF96F3AC80F5BD8D96020232B2BB9" xlink:to="loc_prth_TheEarnoutIncentivePlanMember_47F8F82056005EF21654602023318007" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_666E7D9A6F8671CE1C6D6020233140BF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E379B92FE31BC5BC8D7B6020233107B4" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_666E7D9A6F8671CE1C6D6020233140BF" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/EquityBasedCompensationPlansTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/EquityNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaap_ClassOfStockLineItems_B43E3AB7F494517D923FA1C76C7CCBFC" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_66C6EF6B77EB5341BF447792A5CB03E7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_B43E3AB7F494517D923FA1C76C7CCBFC" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_66C6EF6B77EB5341BF447792A5CB03E7" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_28B85269C78E509CBC12C8A159936FBE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_66C6EF6B77EB5341BF447792A5CB03E7" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_28B85269C78E509CBC12C8A159936FBE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_4C11EDA9333BEA72243677D4E4B31415_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_28B85269C78E509CBC12C8A159936FBE" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_4C11EDA9333BEA72243677D4E4B31415_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_3D26F8E93A9451A889E1F73B48D7CD0D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_28B85269C78E509CBC12C8A159936FBE" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_3D26F8E93A9451A889E1F73B48D7CD0D" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_MIAcquisitionsWarrantsPublicMember" xlink:label="loc_prth_MIAcquisitionsWarrantsPublicMember_FDF91A4688285BF39EE318B7CB2F22BC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_3D26F8E93A9451A889E1F73B48D7CD0D" xlink:to="loc_prth_MIAcquisitionsWarrantsPublicMember_FDF91A4688285BF39EE318B7CB2F22BC" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_MIAcquisitionsWarrantsPrivateMember" xlink:label="loc_prth_MIAcquisitionsWarrantsPrivateMember_85154A8ED594598695534A2FAF9087E4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_3D26F8E93A9451A889E1F73B48D7CD0D" xlink:to="loc_prth_MIAcquisitionsWarrantsPrivateMember_85154A8ED594598695534A2FAF9087E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VestingAxis" xlink:label="loc_us-gaap_VestingAxis_A6CD682A960253DAAD811E78852A4017" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_66C6EF6B77EB5341BF447792A5CB03E7" xlink:to="loc_us-gaap_VestingAxis_A6CD682A960253DAAD811E78852A4017" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VestingDomain" xlink:label="loc_us-gaap_VestingDomain_A9D891C4BD07BC6ED95477D4E4B4A1A1_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_A6CD682A960253DAAD811E78852A4017" xlink:to="loc_us-gaap_VestingDomain_A9D891C4BD07BC6ED95477D4E4B4A1A1_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VestingDomain" xlink:label="loc_us-gaap_VestingDomain_91F29705A03455BDBC0F9903B03C47F2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_A6CD682A960253DAAD811E78852A4017" xlink:to="loc_us-gaap_VestingDomain_91F29705A03455BDBC0F9903B03C47F2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_300F81CEEA715DA39BB83893D205EBEA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_91F29705A03455BDBC0F9903B03C47F2" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_300F81CEEA715DA39BB83893D205EBEA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_0F52AC556BBE52B7BB06B6FBBD704622" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_91F29705A03455BDBC0F9903B03C47F2" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_0F52AC556BBE52B7BB06B6FBBD704622" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_36FF814FA11F5A69ACCD0E4F0309596D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_B43E3AB7F494517D923FA1C76C7CCBFC" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_36FF814FA11F5A69ACCD0E4F0309596D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare" xlink:label="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_28CE38690AA55BE2AA8FC842B9E141BF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_B43E3AB7F494517D923FA1C76C7CCBFC" xlink:to="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_28CE38690AA55BE2AA8FC842B9E141BF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_5629867FBFFA575BB0EE20F1AAE482A8" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_B43E3AB7F494517D923FA1C76C7CCBFC" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_5629867FBFFA575BB0EE20F1AAE482A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightOutstanding" xlink:label="loc_us-gaap_ClassOfWarrantOrRightOutstanding_2CBD8355C0D75E24A3BEECA0581AA5AD" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_B43E3AB7F494517D923FA1C76C7CCBFC" xlink:to="loc_us-gaap_ClassOfWarrantOrRightOutstanding_2CBD8355C0D75E24A3BEECA0581AA5AD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_3E221B62A0275708B8B94E9E49B5348E" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_B43E3AB7F494517D923FA1C76C7CCBFC" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_3E221B62A0275708B8B94E9E49B5348E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_9A03D7BF8FEF5AE7B4C2E91B3931A126" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_B43E3AB7F494517D923FA1C76C7CCBFC" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_9A03D7BF8FEF5AE7B4C2E91B3931A126" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_CommonStockSharesAuthorizedEarnOutConsideration" xlink:label="loc_prth_CommonStockSharesAuthorizedEarnOutConsideration_771791C98C4A5252AABB1B32A9CB428F" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_B43E3AB7F494517D923FA1C76C7CCBFC" xlink:to="loc_prth_CommonStockSharesAuthorizedEarnOutConsideration_771791C98C4A5252AABB1B32A9CB428F" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_EarnOutConsiderationFutureMinimumEBITDA" xlink:label="loc_prth_EarnOutConsiderationFutureMinimumEBITDA_C4526079F47958139160FDB5F0C52409" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_B43E3AB7F494517D923FA1C76C7CCBFC" xlink:to="loc_prth_EarnOutConsiderationFutureMinimumEBITDA_C4526079F47958139160FDB5F0C52409" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_EarnOutConsiderationMinimumStockPrice" xlink:label="loc_prth_EarnOutConsiderationMinimumStockPrice_2366911FE9E8507A91B669E433AB3E90" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_B43E3AB7F494517D923FA1C76C7CCBFC" xlink:to="loc_prth_EarnOutConsiderationMinimumStockPrice_2366911FE9E8507A91B669E433AB3E90" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_CommonStockSharesIssuedEarnOutConsideration" xlink:label="loc_prth_CommonStockSharesIssuedEarnOutConsideration_3DA6EEF9DDCC52C982CDF74D7474DC8E" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_B43E3AB7F494517D923FA1C76C7CCBFC" xlink:to="loc_prth_CommonStockSharesIssuedEarnOutConsideration_3DA6EEF9DDCC52C982CDF74D7474DC8E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/FairValue" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/FairValueNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_34E701F842E0A386F67B5B6EEB744B79" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2C40EB5A8E66D2BCEB7A5B6EEB70E1F4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_34E701F842E0A386F67B5B6EEB744B79" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2C40EB5A8E66D2BCEB7A5B6EEB70E1F4" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_F4C683D83C165E979A825B6EEB71F00A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2C40EB5A8E66D2BCEB7A5B6EEB70E1F4" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_F4C683D83C165E979A825B6EEB71F00A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_E98BC90A7322E3F413D35B6EEB71981C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_F4C683D83C165E979A825B6EEB71F00A" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_E98BC90A7322E3F413D35B6EEB71981C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_E98BC90A7322E3F413D35B6EEB71981C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_F4C683D83C165E979A825B6EEB71F00A" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_E98BC90A7322E3F413D35B6EEB71981C" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_GS1.8WarrantsMember" xlink:label="loc_prth_GS1.8WarrantsMember_A9CFCBFF3CB92F6E36CB5B6EEB714C10" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_E98BC90A7322E3F413D35B6EEB71981C" xlink:to="loc_prth_GS1.8WarrantsMember_A9CFCBFF3CB92F6E36CB5B6EEB714C10" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_GS2.2WarrantsMember" xlink:label="loc_prth_GS2.2WarrantsMember_819600987D5844A2C4955B6EEB71D8CB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_E98BC90A7322E3F413D35B6EEB71981C" xlink:to="loc_prth_GS2.2WarrantsMember_819600987D5844A2C4955B6EEB71D8CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_A79966B102AC014EB05A5B6EEB725E27" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2C40EB5A8E66D2BCEB7A5B6EEB70E1F4" xlink:to="loc_us-gaap_StatementClassOfStockAxis_A79966B102AC014EB05A5B6EEB725E27" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_2C668436F820646994475B6EEB72BB7F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_A79966B102AC014EB05A5B6EEB725E27" xlink:to="loc_us-gaap_ClassOfStockDomain_2C668436F820646994475B6EEB72BB7F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_2C668436F820646994475B6EEB72BB7F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_A79966B102AC014EB05A5B6EEB725E27" xlink:to="loc_us-gaap_ClassOfStockDomain_2C668436F820646994475B6EEB72BB7F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_CCE3255B1875FFC1BD7F5B6EEB72EC64" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_2C668436F820646994475B6EEB72BB7F" xlink:to="loc_us-gaap_CommonClassAMember_CCE3255B1875FFC1BD7F5B6EEB72EC64" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaap_FinancialInstrumentAxis_635C7B63AB054DA23B6B5B6EEB725156" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2C40EB5A8E66D2BCEB7A5B6EEB70E1F4" xlink:to="loc_us-gaap_FinancialInstrumentAxis_635C7B63AB054DA23B6B5B6EEB725156" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_FF4402CCFEE846E3BEA65B6EEB72A491_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_635C7B63AB054DA23B6B5B6EEB725156" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_FF4402CCFEE846E3BEA65B6EEB72A491_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_FF4402CCFEE846E3BEA65B6EEB72A491" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_635C7B63AB054DA23B6B5B6EEB725156" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_FF4402CCFEE846E3BEA65B6EEB72A491" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaap_WarrantMember_6A8B7F092AECE80E6F5B5B6EEB733FE1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_FF4402CCFEE846E3BEA65B6EEB72A491" xlink:to="loc_us-gaap_WarrantMember_6A8B7F092AECE80E6F5B5B6EEB733FE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_E7262191DF95A75E7B545B6EEB7353D3" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2C40EB5A8E66D2BCEB7A5B6EEB70E1F4" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_E7262191DF95A75E7B545B6EEB7353D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8293271B181221BAF3E45B6EEB732460_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_E7262191DF95A75E7B545B6EEB7353D3" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8293271B181221BAF3E45B6EEB732460_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8293271B181221BAF3E45B6EEB732460" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_E7262191DF95A75E7B545B6EEB7353D3" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8293271B181221BAF3E45B6EEB732460" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_PriorityPaymentSystemsTechPartnersAndPriorityPaymentSystemsNortheastMember" xlink:label="loc_prth_PriorityPaymentSystemsTechPartnersAndPriorityPaymentSystemsNortheastMember_F48D83FFA75BBB4DB8CC5B6EEB733D2D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8293271B181221BAF3E45B6EEB732460" xlink:to="loc_prth_PriorityPaymentSystemsTechPartnersAndPriorityPaymentSystemsNortheastMember_F48D83FFA75BBB4DB8CC5B6EEB733D2D" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_ClassOfWarrantOrRightPercentageOfOutstandingStockAvailableForPurchase" xlink:label="loc_prth_ClassOfWarrantOrRightPercentageOfOutstandingStockAvailableForPurchase_057F8808D5159BCAE1535B6EEB74E8FD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_34E701F842E0A386F67B5B6EEB744B79" xlink:to="loc_prth_ClassOfWarrantOrRightPercentageOfOutstandingStockAvailableForPurchase_057F8808D5159BCAE1535B6EEB74E8FD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WarrantsAndRightsOutstandingTerm" xlink:label="loc_us-gaap_WarrantsAndRightsOutstandingTerm_54208F1610FB4A5926FD5B6EEB743925" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_34E701F842E0A386F67B5B6EEB744B79" xlink:to="loc_us-gaap_WarrantsAndRightsOutstandingTerm_54208F1610FB4A5926FD5B6EEB743925" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_9802398FF047208946615B6EEB74911D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_34E701F842E0A386F67B5B6EEB744B79" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_9802398FF047208946615B6EEB74911D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease_BDA6D31B611E3B1D46E75B6EEB7561A7" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_34E701F842E0A386F67B5B6EEB744B79" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease_BDA6D31B611E3B1D46E75B6EEB7561A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsForRepurchaseOfWarrants" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfWarrants_958804ACB235B08D61325B6EEB750024" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_34E701F842E0A386F67B5B6EEB744B79" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfWarrants_958804ACB235B08D61325B6EEB750024" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_50DDBA5D409C8345B9AC5B6EEB754C92" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_34E701F842E0A386F67B5B6EEB744B79" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_50DDBA5D409C8345B9AC5B6EEB754C92" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NotesReceivableFairValueDisclosure" xlink:label="loc_us-gaap_NotesReceivableFairValueDisclosure_141B7DAEF05EA5416F725B6EEB75E023" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_34E701F842E0A386F67B5B6EEB744B79" xlink:to="loc_us-gaap_NotesReceivableFairValueDisclosure_141B7DAEF05EA5416F725B6EEB75E023" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/FairValueRollforwardDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_781560CB1FBCBE87583566E4974A6023" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_C3D4DDB8602CE1064DFB66E49747EC92" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_781560CB1FBCBE87583566E4974A6023" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_C3D4DDB8602CE1064DFB66E49747EC92" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_3D32FE1BAA6CD5320E4866E497479B9C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_C3D4DDB8602CE1064DFB66E49747EC92" xlink:to="loc_us-gaap_StatementClassOfStockAxis_3D32FE1BAA6CD5320E4866E497479B9C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_384A4520D87350BD170366E497471847_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_3D32FE1BAA6CD5320E4866E497479B9C" xlink:to="loc_us-gaap_ClassOfStockDomain_384A4520D87350BD170366E497471847_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_384A4520D87350BD170366E497471847" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_3D32FE1BAA6CD5320E4866E497479B9C" xlink:to="loc_us-gaap_ClassOfStockDomain_384A4520D87350BD170366E497471847" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_A41640B3F7C1A95E051C66E49747D5D5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_384A4520D87350BD170366E497471847" xlink:to="loc_us-gaap_CommonClassAMember_A41640B3F7C1A95E051C66E49747D5D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_DAF1D36078A906497A2366E497486DCF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_C3D4DDB8602CE1064DFB66E49747EC92" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_DAF1D36078A906497A2366E497486DCF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_7CD7062EA21538820CB766E497480248_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_DAF1D36078A906497A2366E497486DCF" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_7CD7062EA21538820CB766E497480248_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_7CD7062EA21538820CB766E497480248" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_DAF1D36078A906497A2366E497486DCF" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_7CD7062EA21538820CB766E497480248" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_GS1.8WarrantsMember" xlink:label="loc_prth_GS1.8WarrantsMember_65010DB1843B0742C22A66E49748493D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_7CD7062EA21538820CB766E497480248" xlink:to="loc_prth_GS1.8WarrantsMember_65010DB1843B0742C22A66E49748493D" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_GS2.2WarrantsMember" xlink:label="loc_prth_GS2.2WarrantsMember_2D26F75AB0F6EA99CC9A66E497489311" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_7CD7062EA21538820CB766E497480248" xlink:to="loc_prth_GS2.2WarrantsMember_2D26F75AB0F6EA99CC9A66E497489311" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaap_FinancialInstrumentAxis_564EE8B57CFF47D62F9F66E4974956B7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_C3D4DDB8602CE1064DFB66E49747EC92" xlink:to="loc_us-gaap_FinancialInstrumentAxis_564EE8B57CFF47D62F9F66E4974956B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6EE994583321B145458666E4974988B2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_564EE8B57CFF47D62F9F66E4974956B7" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6EE994583321B145458666E4974988B2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6EE994583321B145458666E4974988B2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_564EE8B57CFF47D62F9F66E4974956B7" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6EE994583321B145458666E4974988B2" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_ContingentConsiderationMember" xlink:label="loc_prth_ContingentConsiderationMember_4263B45090C430E7433966E4974915DC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6EE994583321B145458666E4974988B2" xlink:to="loc_prth_ContingentConsiderationMember_4263B45090C430E7433966E4974915DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaap_WarrantMember_872805FB6748DD04111966E49749BBC2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6EE994583321B145458666E4974988B2" xlink:to="loc_us-gaap_WarrantMember_872805FB6748DD04111966E49749BBC2" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_ClassOfWarrantOrRightPercentageOfOutstandingStockAvailableForPurchase" xlink:label="loc_prth_ClassOfWarrantOrRightPercentageOfOutstandingStockAvailableForPurchase_A61D8C4D85C2F16B9AF266E4974AACD4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_781560CB1FBCBE87583566E4974A6023" xlink:to="loc_prth_ClassOfWarrantOrRightPercentageOfOutstandingStockAvailableForPurchase_A61D8C4D85C2F16B9AF266E4974AACD4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_47111FCF05AC58D1B86C66E4974A3609" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_781560CB1FBCBE87583566E4974A6023" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_47111FCF05AC58D1B86C66E4974A3609" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_366A185612FA3B6B3ACF66E4974AD7A7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_47111FCF05AC58D1B86C66E4974A3609" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_366A185612FA3B6B3ACF66E4974AD7A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_47819A93A9874A7B4CDC66E4974A9ECF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_47111FCF05AC58D1B86C66E4974A3609" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_47819A93A9874A7B4CDC66E4974A9ECF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues_AA2964DE0CFF961D1C8966E4974B9006" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_47111FCF05AC58D1B86C66E4974A3609" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues_AA2964DE0CFF961D1C8966E4974B9006" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings_71955194F7A9E18F1F2566E4974B09DA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_47111FCF05AC58D1B86C66E4974A3609" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings_71955194F7A9E18F1F2566E4974B09DA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAdjustmentOfWarrants" xlink:label="loc_us-gaap_FairValueAdjustmentOfWarrants_112BFADF564E475131E466E4974B8B5F" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_47111FCF05AC58D1B86C66E4974A3609" xlink:to="loc_us-gaap_FairValueAdjustmentOfWarrants_112BFADF564E475131E466E4974B8B5F" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/FairValueTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/GoodwillAndIntangibleAssets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/GoodwillAndIntangibleAssetsGoodwillAllocationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillLineItems" xlink:label="loc_us-gaap_GoodwillLineItems_FBC6D1EA47A0543C83143824443E6C87" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_09C940F1283C5B95AB7A7D97C3EFF6F8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_FBC6D1EA47A0543C83143824443E6C87" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_09C940F1283C5B95AB7A7D97C3EFF6F8" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_F76404218B4E5498AE23CD550ADB4ED8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_09C940F1283C5B95AB7A7D97C3EFF6F8" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_F76404218B4E5498AE23CD550ADB4ED8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_668738705C6B4F4FBC538729D52481B3_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_F76404218B4E5498AE23CD550ADB4ED8" xlink:to="loc_us-gaap_SegmentDomain_668738705C6B4F4FBC538729D52481B3_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_907FB49F38BF5A41B259CF50AD4B54CF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_F76404218B4E5498AE23CD550ADB4ED8" xlink:to="loc_us-gaap_SegmentDomain_907FB49F38BF5A41B259CF50AD4B54CF" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_ConsumerPaymentsMember" xlink:label="loc_prth_ConsumerPaymentsMember_17F890DF7F3653A38318F8FA22B861D6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_907FB49F38BF5A41B259CF50AD4B54CF" xlink:to="loc_prth_ConsumerPaymentsMember_17F890DF7F3653A38318F8FA22B861D6" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_CommercialPaymentsAndManagedServicesMember" xlink:label="loc_prth_CommercialPaymentsAndManagedServicesMember_1106E062BB3B508E8F383222EAB9B722" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_907FB49F38BF5A41B259CF50AD4B54CF" xlink:to="loc_prth_CommercialPaymentsAndManagedServicesMember_1106E062BB3B508E8F383222EAB9B722" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_IntegratedPartnersMember" xlink:label="loc_prth_IntegratedPartnersMember_A6B7F313E2C15260BDD010235979830C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_907FB49F38BF5A41B259CF50AD4B54CF" xlink:to="loc_prth_IntegratedPartnersMember_A6B7F313E2C15260BDD010235979830C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_E62825A16BF75E9C867604D6AAE1A65E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_FBC6D1EA47A0543C83143824443E6C87" xlink:to="loc_us-gaap_Goodwill_E62825A16BF75E9C867604D6AAE1A65E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/GoodwillAndIntangibleAssetsIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_10F5F136B3D65C85A34B11CBF5983D6A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_18BEAFCD3ACF595DB2423BBB2E9EAE11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_10F5F136B3D65C85A34B11CBF5983D6A" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_18BEAFCD3ACF595DB2423BBB2E9EAE11" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6DDE56BFDCD4507C8734FFBE76C3CE73" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_18BEAFCD3ACF595DB2423BBB2E9EAE11" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6DDE56BFDCD4507C8734FFBE76C3CE73" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_92C382475CE0AF9F42959161156BD30E_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6DDE56BFDCD4507C8734FFBE76C3CE73" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_92C382475CE0AF9F42959161156BD30E_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_1BE121FCD69D5D5BBD890F0BB884E9B3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6DDE56BFDCD4507C8734FFBE76C3CE73" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_1BE121FCD69D5D5BBD890F0BB884E9B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ServiceAgreementsMember" xlink:label="loc_us-gaap_ServiceAgreementsMember_0D4384FC47365F80B66CB81C1F1D777A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_1BE121FCD69D5D5BBD890F0BB884E9B3" xlink:to="loc_us-gaap_ServiceAgreementsMember_0D4384FC47365F80B66CB81C1F1D777A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_69B48DFED15D54BE8F7C5B49C979758F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_1BE121FCD69D5D5BBD890F0BB884E9B3" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_69B48DFED15D54BE8F7C5B49C979758F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="loc_us-gaap_TradeNamesMember_6DBDB9AEC3EC535BB6A58D37403BD80F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_1BE121FCD69D5D5BBD890F0BB884E9B3" xlink:to="loc_us-gaap_TradeNamesMember_6DBDB9AEC3EC535BB6A58D37403BD80F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_6830961B01CC58A8AA278391734F1F95" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_1BE121FCD69D5D5BBD890F0BB884E9B3" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_6830961B01CC58A8AA278391734F1F95" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_67EDA8E0311251E989C9533905982C75" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_1BE121FCD69D5D5BBD890F0BB884E9B3" xlink:to="loc_us-gaap_CustomerRelationshipsMember_67EDA8E0311251E989C9533905982C75" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_21FE528EE52B5572907669F2889F3F0E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_10F5F136B3D65C85A34B11CBF5983D6A" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_21FE528EE52B5572907669F2889F3F0E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_19DBE479736A5ADEB55FA607AD946E5A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_10F5F136B3D65C85A34B11CBF5983D6A" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_19DBE479736A5ADEB55FA607AD946E5A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_F6638662FB3958C796E63D4092B198B2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_10F5F136B3D65C85A34B11CBF5983D6A" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_F6638662FB3958C796E63D4092B198B2" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/GoodwillAndIntangibleAssetsNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/GoodwillAndIntangibleAssetsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/IncomeTaxes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/IncomeTaxesScheduleOfIncomeTaxBenefitProvisionDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/IncomeTaxesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/LongTermDebt" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/LongTermDebtNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_3283BC8264B6D861C4F260920DB70B2F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_DebtInstrumentTable_3283BC8264B6D861C4F260920DB70B2F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_6100EE75383CEF8C14A560920DB7C483" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3283BC8264B6D861C4F260920DB70B2F" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_6100EE75383CEF8C14A560920DB7C483" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_F93B07D14BCB96F57A4060920DB74756_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_6100EE75383CEF8C14A560920DB7C483" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_F93B07D14BCB96F57A4060920DB74756_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_F93B07D14BCB96F57A4060920DB74756" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_6100EE75383CEF8C14A560920DB7C483" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_F93B07D14BCB96F57A4060920DB74756" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_852D15A5AF0BB7260FAF60920DB76227" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_F93B07D14BCB96F57A4060920DB74756" xlink:to="loc_us-gaap_SubsequentEventMember_852D15A5AF0BB7260FAF60920DB76227" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_6185949B425CDA8E754A60920DB899B9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3283BC8264B6D861C4F260920DB70B2F" xlink:to="loc_us-gaap_DebtInstrumentAxis_6185949B425CDA8E754A60920DB899B9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7DF95B5E094A3192B4C760920DB8BC09_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_6185949B425CDA8E754A60920DB899B9" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7DF95B5E094A3192B4C760920DB8BC09_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7DF95B5E094A3192B4C760920DB8BC09" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_6185949B425CDA8E754A60920DB899B9" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7DF95B5E094A3192B4C760920DB8BC09" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_DelayedDrawMember" xlink:label="loc_prth_DelayedDrawMember_BCCE89D5D3CA3933CD9B60920DB8C904" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_7DF95B5E094A3192B4C760920DB8BC09" xlink:to="loc_prth_DelayedDrawMember_BCCE89D5D3CA3933CD9B60920DB8C904" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_72C6FE134019121C1BEF60920DB85734" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3283BC8264B6D861C4F260920DB70B2F" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_72C6FE134019121C1BEF60920DB85734" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_27D12DDB8612CE5FC95560920DB9C01E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_72C6FE134019121C1BEF60920DB85734" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_27D12DDB8612CE5FC95560920DB9C01E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_27D12DDB8612CE5FC95560920DB9C01E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_72C6FE134019121C1BEF60920DB85734" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_27D12DDB8612CE5FC95560920DB9C01E" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_GoldmanSachsSpecialtyLendingGroupMember" xlink:label="loc_prth_GoldmanSachsSpecialtyLendingGroupMember_FE45122ECE0F9ED673A360920DB93508" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_27D12DDB8612CE5FC95560920DB9C01E" xlink:to="loc_prth_GoldmanSachsSpecialtyLendingGroupMember_FE45122ECE0F9ED673A360920DB93508" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_SyndicateOfLendersMember" xlink:label="loc_prth_SyndicateOfLendersMember_91152BF546F55E817FBA60920DB92F7D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_27D12DDB8612CE5FC95560920DB9C01E" xlink:to="loc_prth_SyndicateOfLendersMember_91152BF546F55E817FBA60920DB92F7D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_7F8E8673FF114FC38C7260920DB9F27A" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3283BC8264B6D861C4F260920DB70B2F" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_7F8E8673FF114FC38C7260920DB9F27A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_93AEB2010EFFBF3588C060920DB96569_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_7F8E8673FF114FC38C7260920DB9F27A" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_93AEB2010EFFBF3588C060920DB96569_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_93AEB2010EFFBF3588C060920DB96569" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_7F8E8673FF114FC38C7260920DB9F27A" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_93AEB2010EFFBF3588C060920DB96569" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditMember" xlink:label="loc_us-gaap_LineOfCreditMember_F7E6AB843F650E4B97C960920DBA7560" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_93AEB2010EFFBF3588C060920DB96569" xlink:to="loc_us-gaap_LineOfCreditMember_F7E6AB843F650E4B97C960920DBA7560" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_3D33AB565D6AA51B394560920DBA43D4" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3283BC8264B6D861C4F260920DB70B2F" xlink:to="loc_us-gaap_CreditFacilityAxis_3D33AB565D6AA51B394560920DBA43D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_F0DB5575EA62E313FC4560920DBA898E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_3D33AB565D6AA51B394560920DBA43D4" xlink:to="loc_us-gaap_CreditFacilityDomain_F0DB5575EA62E313FC4560920DBA898E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_F0DB5575EA62E313FC4560920DBA898E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_3D33AB565D6AA51B394560920DBA43D4" xlink:to="loc_us-gaap_CreditFacilityDomain_F0DB5575EA62E313FC4560920DBA898E" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_TermLoanMember" xlink:label="loc_prth_TermLoanMember_5F59C9A0A3E9BEF7E6BE60920DBA2AEC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_F0DB5575EA62E313FC4560920DBA898E" xlink:to="loc_prth_TermLoanMember_5F59C9A0A3E9BEF7E6BE60920DBA2AEC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_1AB7B8B7B9FF2641720A60920DBB0008" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_F0DB5575EA62E313FC4560920DBA898E" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_1AB7B8B7B9FF2641720A60920DBB0008" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_62E52F1DDD3A549B301760920DBB2D2E" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3283BC8264B6D861C4F260920DB70B2F" xlink:to="loc_us-gaap_VariableRateAxis_62E52F1DDD3A549B301760920DBB2D2E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_08A69B96913F6019CA1960920DBB0F6E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_62E52F1DDD3A549B301760920DBB2D2E" xlink:to="loc_us-gaap_VariableRateDomain_08A69B96913F6019CA1960920DBB0F6E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_08A69B96913F6019CA1960920DBB0F6E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_62E52F1DDD3A549B301760920DBB2D2E" xlink:to="loc_us-gaap_VariableRateDomain_08A69B96913F6019CA1960920DBB0F6E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_30EF09445BACFFE0F1FF60920DBB680C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_08A69B96913F6019CA1960920DBB0F6E" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_30EF09445BACFFE0F1FF60920DBB680C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BaseRateMember" xlink:label="loc_us-gaap_BaseRateMember_AD3EFCB3AD6626CD298B60920DBC1281" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_08A69B96913F6019CA1960920DBB0F6E" xlink:to="loc_us-gaap_BaseRateMember_AD3EFCB3AD6626CD298B60920DBC1281" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_79B7DE5A823A12CFBC0D60920DBC4EB5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_79B7DE5A823A12CFBC0D60920DBC4EB5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_7B53E220D78B64823A3460920DBC1A88" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_7B53E220D78B64823A3460920DBC1A88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeeAmount" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeeAmount_98472212AD835315001760920DBCBF97" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeeAmount_98472212AD835315001760920DBCBF97" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_9BE995539E717A413C6E60920DBC4DFD" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_9BE995539E717A413C6E60920DBC4DFD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_3AEA8D64C9004C71E83660920DBD3687" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_LineOfCredit_3AEA8D64C9004C71E83660920DBD3687" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_DA8206393D0548574AF460920DBD0536" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_DA8206393D0548574AF460920DBD0536" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_97B72055145BAAFD640B60920DBD7371" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_97B72055145BAAFD640B60920DBD7371" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_FF699886493090EE9D2960920DBDA98D" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_FF699886493090EE9D2960920DBDA98D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_282469DCDAFE1F51356060920DBD18BB" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_282469DCDAFE1F51356060920DBD18BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentPeriodicPayment" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPayment_5DDD002A2F59659FA84C60920DBDB8BA" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPayment_5DDD002A2F59659FA84C60920DBDB8BA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaidInKindInterest" xlink:label="loc_us-gaap_PaidInKindInterest_81F2547E0BCCFC0DF31C60920DBE56AB" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_PaidInKindInterest_81F2547E0BCCFC0DF31C60920DBE56AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_DD2049B7527C282A35CC60920DBE6750" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_us-gaap_InterestExpense_DD2049B7527C282A35CC60920DBE6750" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_AmortizationOfDebtDiscountPremiumAndDebtIssuanceCosts" xlink:label="loc_prth_AmortizationOfDebtDiscountPremiumAndDebtIssuanceCosts_3974FF15F220AD5C6C4F60920DBE91CD" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_prth_AmortizationOfDebtDiscountPremiumAndDebtIssuanceCosts_3974FF15F220AD5C6C4F60920DBE91CD" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_DebtCovenantMaximumNetLeverageRatio" xlink:label="loc_prth_DebtCovenantMaximumNetLeverageRatio_BEC7EBC411C79A55A56B60920DBEFF6D" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9151758DDA1D6ED2EA7060920DBCA7A5" xlink:to="loc_prth_DebtCovenantMaximumNetLeverageRatio_BEC7EBC411C79A55A56B60920DBEFF6D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/LongTermDebtRollingMaturitiesOfLongTermDebtDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/LongTermDebtScheduleOfLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_B64E8C1CB9EB5A2895D4F55BCB31643A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_FAB916B92E1853EE860BC33F4C5C739D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_B64E8C1CB9EB5A2895D4F55BCB31643A" xlink:to="loc_us-gaap_DebtInstrumentTable_FAB916B92E1853EE860BC33F4C5C739D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_F6A9CD6500B45293923917A281A7B0E5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_FAB916B92E1853EE860BC33F4C5C739D" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_F6A9CD6500B45293923917A281A7B0E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_F504CB5B437EADDB88537247CC5348B7_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_F6A9CD6500B45293923917A281A7B0E5" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_F504CB5B437EADDB88537247CC5348B7_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_0355B569128E5D409DF1F9E4C4622CB6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_F6A9CD6500B45293923917A281A7B0E5" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_0355B569128E5D409DF1F9E4C4622CB6" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_SyndicateOfLendersMember" xlink:label="loc_prth_SyndicateOfLendersMember_E0710483D1665AC3B93A7D75DED08B53" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_0355B569128E5D409DF1F9E4C4622CB6" xlink:to="loc_prth_SyndicateOfLendersMember_E0710483D1665AC3B93A7D75DED08B53" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_GoldmanSachsSpecialtyLendingGroupMember" xlink:label="loc_prth_GoldmanSachsSpecialtyLendingGroupMember_E8D6941118B75E11B150907B6D2D2B6C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_0355B569128E5D409DF1F9E4C4622CB6" xlink:to="loc_prth_GoldmanSachsSpecialtyLendingGroupMember_E8D6941118B75E11B150907B6D2D2B6C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_CC096A9CD11B52B7B7D02F1994D19A5B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_FAB916B92E1853EE860BC33F4C5C739D" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_CC096A9CD11B52B7B7D02F1994D19A5B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_03E109D6DDD2229FD3267247CC548BF6_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_CC096A9CD11B52B7B7D02F1994D19A5B" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_03E109D6DDD2229FD3267247CC548BF6_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_5C2CC476B05E503AB8D055ACFE7CCBEC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_CC096A9CD11B52B7B7D02F1994D19A5B" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_5C2CC476B05E503AB8D055ACFE7CCBEC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditMember" xlink:label="loc_us-gaap_LineOfCreditMember_43F9D8350FDF546CB3220ECA009F581F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5C2CC476B05E503AB8D055ACFE7CCBEC" xlink:to="loc_us-gaap_LineOfCreditMember_43F9D8350FDF546CB3220ECA009F581F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_A7F9356DC1725302B6CEC151FC3F3E81" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_FAB916B92E1853EE860BC33F4C5C739D" xlink:to="loc_us-gaap_CreditFacilityAxis_A7F9356DC1725302B6CEC151FC3F3E81" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_6E2F9F6C3662D2D2512C7247CC520174_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_A7F9356DC1725302B6CEC151FC3F3E81" xlink:to="loc_us-gaap_CreditFacilityDomain_6E2F9F6C3662D2D2512C7247CC520174_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_F484CDBBA39F5EFE804FC7B1E506C68C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_A7F9356DC1725302B6CEC151FC3F3E81" xlink:to="loc_us-gaap_CreditFacilityDomain_F484CDBBA39F5EFE804FC7B1E506C68C" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_TermLoanMember" xlink:label="loc_prth_TermLoanMember_FCE84A581C7A5C4597661918695D408A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_F484CDBBA39F5EFE804FC7B1E506C68C" xlink:to="loc_prth_TermLoanMember_FCE84A581C7A5C4597661918695D408A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_F9A61C701B835E05B6BB47528B19103A" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_FAB916B92E1853EE860BC33F4C5C739D" xlink:to="loc_us-gaap_VariableRateAxis_F9A61C701B835E05B6BB47528B19103A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_FE552E9E040C2E050BF67247CC55FEE1_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_F9A61C701B835E05B6BB47528B19103A" xlink:to="loc_us-gaap_VariableRateDomain_FE552E9E040C2E050BF67247CC55FEE1_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_A4191B5DD0305ACF993DC3CBE499B7FB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_F9A61C701B835E05B6BB47528B19103A" xlink:to="loc_us-gaap_VariableRateDomain_A4191B5DD0305ACF993DC3CBE499B7FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_E657CB51C70F5D10BA30BBC07BD910A4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_A4191B5DD0305ACF993DC3CBE499B7FB" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_E657CB51C70F5D10BA30BBC07BD910A4" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_PaymentInKindInterestRateMember" xlink:label="loc_prth_PaymentInKindInterestRateMember_40EA856A30D559E384EA920663580AF5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_A4191B5DD0305ACF993DC3CBE499B7FB" xlink:to="loc_prth_PaymentInKindInterestRateMember_40EA856A30D559E384EA920663580AF5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_140B3984FB9D580D82DFFD4AE4EB89A6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_B64E8C1CB9EB5A2895D4F55BCB31643A" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_140B3984FB9D580D82DFFD4AE4EB89A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtCurrent" xlink:label="loc_us-gaap_LongTermDebtCurrent_603A6EBF6C8B50CF8B837FA03DA699BD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_B64E8C1CB9EB5A2895D4F55BCB31643A" xlink:to="loc_us-gaap_LongTermDebtCurrent_603A6EBF6C8B50CF8B837FA03DA699BD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_07B90877005B551E92CC18CB3576BFB7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_B64E8C1CB9EB5A2895D4F55BCB31643A" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_07B90877005B551E92CC18CB3576BFB7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredFinanceCostsNet" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_545386AB81015066BCFC67478509056C" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_B64E8C1CB9EB5A2895D4F55BCB31643A" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_545386AB81015066BCFC67478509056C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt_9240419E908D5D289DFA485C023282D1" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_B64E8C1CB9EB5A2895D4F55BCB31643A" xlink:to="loc_us-gaap_LongTermDebt_9240419E908D5D289DFA485C023282D1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_952C6A44B3D754F2ABFCF5BB072902D4" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_B64E8C1CB9EB5A2895D4F55BCB31643A" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_952C6A44B3D754F2ABFCF5BB072902D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_142F2E01A5E651A39E121E2F41912462" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_B64E8C1CB9EB5A2895D4F55BCB31643A" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_142F2E01A5E651A39E121E2F41912462" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/LongTermDebtTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/LossPerShare" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/LossPerShareScheduleOfAntidilutiveSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_15849B0920CF289037CD5B81CF17B60C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_3E77BCFF33E700F42A235B81CF149256" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_15849B0920CF289037CD5B81CF17B60C" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_3E77BCFF33E700F42A235B81CF149256" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_A345A20A5C9795E515F75B81CF14A188" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_3E77BCFF33E700F42A235B81CF149256" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_A345A20A5C9795E515F75B81CF14A188" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_1161614C120A6CABE6705B81CF15B5BF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_A345A20A5C9795E515F75B81CF14A188" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_1161614C120A6CABE6705B81CF15B5BF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_1161614C120A6CABE6705B81CF15B5BF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_A345A20A5C9795E515F75B81CF14A188" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_1161614C120A6CABE6705B81CF15B5BF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaap_WarrantMember_4B10934758981FCE4A665B81CF1577D4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_1161614C120A6CABE6705B81CF15B5BF" xlink:to="loc_us-gaap_WarrantMember_4B10934758981FCE4A665B81CF1577D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_FC92FCEC93044602B3FF5B81CF15BE8A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_1161614C120A6CABE6705B81CF15B5BF" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_FC92FCEC93044602B3FF5B81CF15BE8A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_CF03632D7BBF3E25A5F85B81CF155E22" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_1161614C120A6CABE6705B81CF15B5BF" xlink:to="loc_us-gaap_EmployeeStockOptionMember_CF03632D7BBF3E25A5F85B81CF155E22" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_EarnoutIncentiveAwardsMember" xlink:label="loc_prth_EarnoutIncentiveAwardsMember_370FE8B1BB67B6FA9E075B81CF16CE63" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_1161614C120A6CABE6705B81CF15B5BF" xlink:to="loc_prth_EarnoutIncentiveAwardsMember_370FE8B1BB67B6FA9E075B81CF16CE63" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_EarnoutIncentiveAwardsSubjectToFutureIssuanceMember" xlink:label="loc_prth_EarnoutIncentiveAwardsSubjectToFutureIssuanceMember_C4C6CA33FB38686420315B81CF162678" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_1161614C120A6CABE6705B81CF15B5BF" xlink:to="loc_prth_EarnoutIncentiveAwardsSubjectToFutureIssuanceMember_C4C6CA33FB38686420315B81CF162678" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_BE95D3BAF955EB4538155B81CF172601" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_15849B0920CF289037CD5B81CF17B60C" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_BE95D3BAF955EB4538155B81CF172601" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/LossPerShareScheduleOfEarningsPerShareDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/LossPerShareTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/NatureOfBusinessAndBasisOfPresentation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/NatureOfBusinessAndBasisOfPresentationNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/NatureOfBusinessAndBasisOfPresentationPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/PropertyEquipmentAndSoftware" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/PropertyEquipmentAndSoftwareNarrativeAndScheduleOfPropertyEquipmentAndSoftwareDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_940CA1FB10BC51658A8A47D777143D56" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_29DB0E0502EA54B381F38340F8608102" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_940CA1FB10BC51658A8A47D777143D56" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_29DB0E0502EA54B381F38340F8608102" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_95F36D161B3E5E488626BD450427553D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_29DB0E0502EA54B381F38340F8608102" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_95F36D161B3E5E488626BD450427553D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1B796674B620090E36C77247CC758262_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_95F36D161B3E5E488626BD450427553D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1B796674B620090E36C77247CC758262_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_D1435B85E9475424BA1BC37B805102BF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_95F36D161B3E5E488626BD450427553D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_D1435B85E9475424BA1BC37B805102BF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_05C97D1CFBDA5260AFCFE3E3E707D414" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_D1435B85E9475424BA1BC37B805102BF" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_05C97D1CFBDA5260AFCFE3E3E707D414" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquipmentMember" xlink:label="loc_us-gaap_EquipmentMember_2D294E9CC1D4581B8A922E4956AC6E79" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_D1435B85E9475424BA1BC37B805102BF" xlink:to="loc_us-gaap_EquipmentMember_2D294E9CC1D4581B8A922E4956AC6E79" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_5152ABB6DB06593CAF7F35CAB77D76F9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_D1435B85E9475424BA1BC37B805102BF" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_5152ABB6DB06593CAF7F35CAB77D76F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_5AC9C9D7BEC0515AB62CB587D920269B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_D1435B85E9475424BA1BC37B805102BF" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_5AC9C9D7BEC0515AB62CB587D920269B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_825FAAFC08BF5141A749181013DC1C1C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_29DB0E0502EA54B381F38340F8608102" xlink:to="loc_srt_RangeAxis_825FAAFC08BF5141A749181013DC1C1C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_4F5C8204C570F3DDBAFE7247CC769516_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_825FAAFC08BF5141A749181013DC1C1C" xlink:to="loc_srt_RangeMember_4F5C8204C570F3DDBAFE7247CC769516_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_557C6E3E2EED5250A3266122747B4449" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_825FAAFC08BF5141A749181013DC1C1C" xlink:to="loc_srt_RangeMember_557C6E3E2EED5250A3266122747B4449" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_6298F4305D615EB49074A22C4EE2CF4F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_557C6E3E2EED5250A3266122747B4449" xlink:to="loc_srt_MinimumMember_6298F4305D615EB49074A22C4EE2CF4F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_684003F1FEE6514196E88F13F8E461F9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_557C6E3E2EED5250A3266122747B4449" xlink:to="loc_srt_MaximumMember_684003F1FEE6514196E88F13F8E461F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_3F9EB05A6EB05BFC92B3738FD688F92C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_940CA1FB10BC51658A8A47D777143D56" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_3F9EB05A6EB05BFC92B3738FD688F92C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_9BFE554A89185701B1EF1BA2D6F62C70" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_940CA1FB10BC51658A8A47D777143D56" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_9BFE554A89185701B1EF1BA2D6F62C70" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_B052FFAE9E1D563AB53625BB20F89C4E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_940CA1FB10BC51658A8A47D777143D56" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_B052FFAE9E1D563AB53625BB20F89C4E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_A102614762655A8E99AA11CD46312DB3" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_940CA1FB10BC51658A8A47D777143D56" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_A102614762655A8E99AA11CD46312DB3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaap_Depreciation_7EC89C13B29D582F9143A40EBF6332CC" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_940CA1FB10BC51658A8A47D777143D56" xlink:to="loc_us-gaap_Depreciation_7EC89C13B29D582F9143A40EBF6332CC" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/PropertyEquipmentAndSoftwareTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/ReconciliationOfStockholdersEquityDeficitAndNonControllingInterest" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/ReconciliationOfStockholdersEquityDeficitAndNonControllingInterestEquityReconciliationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaap_ClassOfStockLineItems_9CE03C7FEEFE299859786020236E47D2" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_4AFFE892DCFC4DB23B6E6020236BD415" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_9CE03C7FEEFE299859786020236E47D2" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_4AFFE892DCFC4DB23B6E6020236BD415" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_0D699BBB8998939CD1586020236C1130" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_4AFFE892DCFC4DB23B6E6020236BD415" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_0D699BBB8998939CD1586020236C1130" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_41BC03EE59FD9FE54FC96020236CB2A0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_0D699BBB8998939CD1586020236C1130" xlink:to="loc_us-gaap_EquityComponentDomain_41BC03EE59FD9FE54FC96020236CB2A0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_41BC03EE59FD9FE54FC96020236CB2A0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_0D699BBB8998939CD1586020236C1130" xlink:to="loc_us-gaap_EquityComponentDomain_41BC03EE59FD9FE54FC96020236CB2A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockMember" xlink:label="loc_us-gaap_PreferredStockMember_9BB0A6DDB3039E03529F6020236CBA35" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_41BC03EE59FD9FE54FC96020236CB2A0" xlink:to="loc_us-gaap_PreferredStockMember_9BB0A6DDB3039E03529F6020236CBA35" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_6AA57936CE07F4814B1F6020236D506C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_41BC03EE59FD9FE54FC96020236CB2A0" xlink:to="loc_us-gaap_CommonStockMember_6AA57936CE07F4814B1F6020236D506C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockMember" xlink:label="loc_us-gaap_TreasuryStockMember_BFBB280640AC0F4F99376020236D665D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_41BC03EE59FD9FE54FC96020236CB2A0" xlink:to="loc_us-gaap_TreasuryStockMember_BFBB280640AC0F4F99376020236D665D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_F0484586E77EBBBBE62F6020236DA609" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_41BC03EE59FD9FE54FC96020236CB2A0" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_F0484586E77EBBBBE62F6020236DA609" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_A43242B2E03A110243FA6020236DEA00" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_41BC03EE59FD9FE54FC96020236CB2A0" xlink:to="loc_us-gaap_RetainedEarningsMember_A43242B2E03A110243FA6020236DEA00" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ParentMember" xlink:label="loc_us-gaap_ParentMember_771DAA031297D2B426B06020236DA007" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_41BC03EE59FD9FE54FC96020236CB2A0" xlink:to="loc_us-gaap_ParentMember_771DAA031297D2B426B06020236DA007" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NoncontrollingInterestMember" xlink:label="loc_us-gaap_NoncontrollingInterestMember_4BD27D73EA79CA73933F6020236E672E" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_41BC03EE59FD9FE54FC96020236CB2A0" xlink:to="loc_us-gaap_NoncontrollingInterestMember_4BD27D73EA79CA73933F6020236E672E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9CE03C7FEEFE299859786020236E47D2" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding_752FB3045F7F412A848A6020236E4EA2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_SharesOutstanding_752FB3045F7F412A848A6020236E4EA2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_220FDE2AFEFFF44D3DD06020236E5CF7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_220FDE2AFEFFF44D3DD06020236E5CF7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Dividends" xlink:label="loc_us-gaap_Dividends_FA606FDC88F9E19CDE436020236F08CF" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_Dividends_FA606FDC88F9E19CDE436020236F08CF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRedeemedOrCalledDuringPeriodShares" xlink:label="loc_us-gaap_StockRedeemedOrCalledDuringPeriodShares_32CB831C7B892FC0CD0A6020236FFF69" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_StockRedeemedOrCalledDuringPeriodShares_32CB831C7B892FC0CD0A6020236FFF69" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRedeemedOrCalledDuringPeriodValue" xlink:label="loc_us-gaap_StockRedeemedOrCalledDuringPeriodValue_6DCACC4D16E6447317A46020236F3D44" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_StockRedeemedOrCalledDuringPeriodValue_6DCACC4D16E6447317A46020236F3D44" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfUnits" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfUnits_90B8702A50D2812F26F06020236F3774" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfUnits_90B8702A50D2812F26F06020236F3774" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_B7273520D12B0CA4A01F6020236F539B" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_B7273520D12B0CA4A01F6020236F539B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_B8C65B6FA59175CC85FE6020236F9B0C" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_B8C65B6FA59175CC85FE6020236F9B0C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_CBC7386B7BE7D1E899546020237083A3" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_CBC7386B7BE7D1E899546020237083A3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_45DD810D8E6FB307ED8F60202370A403" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_45DD810D8E6FB307ED8F60202370A403" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_E257E7D2EF57DB5A7BC660202370CB3B" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_E257E7D2EF57DB5A7BC660202370CB3B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_4FA6C93BE16E89A0A0DC60202370F495" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_4FA6C93BE16E89A0A0DC60202370F495" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_EffectsOfFoundersShareAgreementShares" xlink:label="loc_prth_EffectsOfFoundersShareAgreementShares_681996AC168761F05306607719A2C966" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_prth_EffectsOfFoundersShareAgreementShares_681996AC168761F05306607719A2C966" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_EffectsOfFoundersShareAgreementValue" xlink:label="loc_prth_EffectsOfFoundersShareAgreementValue_D9B63BF403D3F20C27F660796BE32390" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_prth_EffectsOfFoundersShareAgreementValue_D9B63BF403D3F20C27F660796BE32390" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RecapitalizationCosts" xlink:label="loc_us-gaap_RecapitalizationCosts_D20DAFEF289B7EB8BB60607A489070D7" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_RecapitalizationCosts_D20DAFEF289B7EB8BB60607A489070D7" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_AdjustmentsToAdditionalPaidInCapitalIncomeTaxEffectLossOfPartnershipStatus" xlink:label="loc_prth_AdjustmentsToAdditionalPaidInCapitalIncomeTaxEffectLossOfPartnershipStatus_5341D00B1E4B51858152602023711CAC" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_prth_AdjustmentsToAdditionalPaidInCapitalIncomeTaxEffectLossOfPartnershipStatus_5341D00B1E4B51858152602023711CAC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_6089DA39FCB301BC615E60202371EEE1" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_6089DA39FCB301BC615E60202371EEE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_25708C3C83E7E467552B60202371D671" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_25708C3C83E7E467552B60202371D671" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_2E9260BEC18539D3E3DD602023719269" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_NetIncomeLoss_2E9260BEC18539D3E3DD602023719269" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance_D88913EF91C8E795C22B602023719F12" xlink:type="locator" />
    <link:definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_43F518C857BC25C9E7116020236E4AD2" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance_D88913EF91C8E795C22B602023719F12" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/ReconciliationOfStockholdersEquityDeficitAndNonControllingInterestNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/ReconciliationOfStockholdersEquityDeficitAndNonControllingInterestTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/RelatedPartyAndOtherTransactions" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/RelatedPartyAndOtherTransactionsNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SegmentInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SegmentInformationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_C991B07831025C408E4836FBD8475609" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_A82A3800FAE154BEB99CD3A1FBE64FEF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_C991B07831025C408E4836FBD8475609" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_A82A3800FAE154BEB99CD3A1FBE64FEF" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_871F9E7D0534588D9A9716E099391922" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_A82A3800FAE154BEB99CD3A1FBE64FEF" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_871F9E7D0534588D9A9716E099391922" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_3CE3B96401889B38E3E18B3C39E35437_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_871F9E7D0534588D9A9716E099391922" xlink:to="loc_us-gaap_SegmentDomain_3CE3B96401889B38E3E18B3C39E35437_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_3B57C1BBD48152509883B7D1654E957D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_871F9E7D0534588D9A9716E099391922" xlink:to="loc_us-gaap_SegmentDomain_3B57C1BBD48152509883B7D1654E957D" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_CommercialPaymentsAndManagedServicesMember" xlink:label="loc_prth_CommercialPaymentsAndManagedServicesMember_3878D5D728105EEEBEE2FD3940A1B731" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_3B57C1BBD48152509883B7D1654E957D" xlink:to="loc_prth_CommercialPaymentsAndManagedServicesMember_3878D5D728105EEEBEE2FD3940A1B731" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:label="loc_us-gaap_NumberOfReportableSegments_A95910690D4F51BD8990B301EBC01867" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_C991B07831025C408E4836FBD8475609" xlink:to="loc_us-gaap_NumberOfReportableSegments_A95910690D4F51BD8990B301EBC01867" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SegmentInformationReconciliationOfTotalOperatingIncomeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_24D90D2ECF12E7EB818039B0698A3179" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_CE807B08CCA47BE44F6439B0698993A1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_24D90D2ECF12E7EB818039B0698A3179" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_CE807B08CCA47BE44F6439B0698993A1" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_F26078B56B1E7FE1F8DB39B06989270C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_CE807B08CCA47BE44F6439B0698993A1" xlink:to="loc_srt_ConsolidationItemsAxis_F26078B56B1E7FE1F8DB39B06989270C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_E214B6A8AC294C68C0B039B0698966AC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_F26078B56B1E7FE1F8DB39B06989270C" xlink:to="loc_srt_ConsolidationItemsDomain_E214B6A8AC294C68C0B039B0698966AC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_E214B6A8AC294C68C0B039B0698966AC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_F26078B56B1E7FE1F8DB39B06989270C" xlink:to="loc_srt_ConsolidationItemsDomain_E214B6A8AC294C68C0B039B0698966AC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_6D43D82641E6DAFDF74F39B0698A5B7B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_E214B6A8AC294C68C0B039B0698966AC" xlink:to="loc_us-gaap_OperatingSegmentsMember_6D43D82641E6DAFDF74F39B0698A5B7B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_A8BD5F492AC685C8138139B0698A02D3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_E214B6A8AC294C68C0B039B0698966AC" xlink:to="loc_us-gaap_CorporateNonSegmentMember_A8BD5F492AC685C8138139B0698A02D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_64E7AFD304A05BDDAA0139B0698A5B78" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_24D90D2ECF12E7EB818039B0698A3179" xlink:to="loc_us-gaap_OperatingIncomeLoss_64E7AFD304A05BDDAA0139B0698A5B78" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_975EE13CB77D15EDA04139B0698B1850" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_24D90D2ECF12E7EB818039B0698A3179" xlink:to="loc_us-gaap_InterestExpense_975EE13CB77D15EDA04139B0698B1850" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_505AF03E81543AF0FE0939B0698B5C11" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_24D90D2ECF12E7EB818039B0698A3179" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_505AF03E81543AF0FE0939B0698B5C11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_6A990A953A1402F3AD5F39B0698B6D55" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_24D90D2ECF12E7EB818039B0698A3179" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_6A990A953A1402F3AD5F39B0698B6D55" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_DB6DE4BE6A741106050139B0698B7F37" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_24D90D2ECF12E7EB818039B0698A3179" xlink:to="loc_us-gaap_NetIncomeLoss_DB6DE4BE6A741106050139B0698B7F37" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SegmentInformationScheduleOfSegmentReportingInformationBySegmentDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_704D0AA164FA555E8CCADE752E5DC02C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_87077FBDE92B511293E21265759E9E35" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_704D0AA164FA555E8CCADE752E5DC02C" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_87077FBDE92B511293E21265759E9E35" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_6A2F313A3EBA5D38BDEE195FEE0DDC15" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_87077FBDE92B511293E21265759E9E35" xlink:to="loc_srt_ConsolidationItemsAxis_6A2F313A3EBA5D38BDEE195FEE0DDC15" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_A42E9B34880996BF36258729D473EAA2_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_6A2F313A3EBA5D38BDEE195FEE0DDC15" xlink:to="loc_srt_ConsolidationItemsDomain_A42E9B34880996BF36258729D473EAA2_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_34ADF53DCA805FBAB3B3F2015BEBE36D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_6A2F313A3EBA5D38BDEE195FEE0DDC15" xlink:to="loc_srt_ConsolidationItemsDomain_34ADF53DCA805FBAB3B3F2015BEBE36D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_CA7C233A24AE5DCDB253DB404EA69275" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_34ADF53DCA805FBAB3B3F2015BEBE36D" xlink:to="loc_us-gaap_OperatingSegmentsMember_CA7C233A24AE5DCDB253DB404EA69275" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_8F78AFAE21245DBF993CE644ABDB939E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_34ADF53DCA805FBAB3B3F2015BEBE36D" xlink:to="loc_us-gaap_CorporateNonSegmentMember_8F78AFAE21245DBF993CE644ABDB939E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_B4D4B76902CF5A7C84FB8EBE1335C102" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_87077FBDE92B511293E21265759E9E35" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_B4D4B76902CF5A7C84FB8EBE1335C102" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_96FEEF6C016F0D67BD9E8729D474892A_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_B4D4B76902CF5A7C84FB8EBE1335C102" xlink:to="loc_us-gaap_SegmentDomain_96FEEF6C016F0D67BD9E8729D474892A_FFC2FF5E56B9571E92E4DC1961ACB353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_7D20D2EDA68551EFB4F83558B161C9D8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_B4D4B76902CF5A7C84FB8EBE1335C102" xlink:to="loc_us-gaap_SegmentDomain_7D20D2EDA68551EFB4F83558B161C9D8" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_ConsumerPaymentsMember" xlink:label="loc_prth_ConsumerPaymentsMember_FEF0F48F5E5953D2AA4CEBE20F745301" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_7D20D2EDA68551EFB4F83558B161C9D8" xlink:to="loc_prth_ConsumerPaymentsMember_FEF0F48F5E5953D2AA4CEBE20F745301" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_CommercialPaymentsAndManagedServicesMember" xlink:label="loc_prth_CommercialPaymentsAndManagedServicesMember_66F124484EBA5E59956B7E99A873E8A2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_7D20D2EDA68551EFB4F83558B161C9D8" xlink:to="loc_prth_CommercialPaymentsAndManagedServicesMember_66F124484EBA5E59956B7E99A873E8A2" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_IntegratedPartnersMember" xlink:label="loc_prth_IntegratedPartnersMember_CBC5E68BD12F50DB9628F3C27FC20420" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_7D20D2EDA68551EFB4F83558B161C9D8" xlink:to="loc_prth_IntegratedPartnersMember_CBC5E68BD12F50DB9628F3C27FC20420" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenuesAbstract" xlink:label="loc_us-gaap_RevenuesAbstract_E1A24E5B396E5E349A2DE31CD8867519" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_704D0AA164FA555E8CCADE752E5DC02C" xlink:to="loc_us-gaap_RevenuesAbstract_E1A24E5B396E5E349A2DE31CD8867519" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_6F388111251E5ED5AE458578517E74B3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_E1A24E5B396E5E349A2DE31CD8867519" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_6F388111251E5ED5AE458578517E74B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLossAbstract" xlink:label="loc_us-gaap_NetIncomeLossAbstract_0187B9603B3D5314AA27234809FE112B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_704D0AA164FA555E8CCADE752E5DC02C" xlink:to="loc_us-gaap_NetIncomeLossAbstract_0187B9603B3D5314AA27234809FE112B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_3F274546A350554EB431C5F23E1752F3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_0187B9603B3D5314AA27234809FE112B" xlink:to="loc_us-gaap_OperatingIncomeLoss_3F274546A350554EB431C5F23E1752F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DepreciationAmortizationAndAccretionNetAbstract" xlink:label="loc_us-gaap_DepreciationAmortizationAndAccretionNetAbstract_FB764A4430425F8887573815F0EFAE67" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_704D0AA164FA555E8CCADE752E5DC02C" xlink:to="loc_us-gaap_DepreciationAmortizationAndAccretionNetAbstract_FB764A4430425F8887573815F0EFAE67" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DepreciationAndAmortization" xlink:label="loc_us-gaap_DepreciationAndAmortization_CF7F1030260A5D2CB0DB9453301E9F65" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DepreciationAmortizationAndAccretionNetAbstract_FB764A4430425F8887573815F0EFAE67" xlink:to="loc_us-gaap_DepreciationAndAmortization_CF7F1030260A5D2CB0DB9453301E9F65" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SegmentInformationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SettlementAssetsAndObligations" xlink:type="extended" />
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SettlementAssetsAndObligationsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_15B12D109886DC83DD6C922042FFDB9C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_F03C8C87FF1C212F8277922042FDDDB8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_15B12D109886DC83DD6C922042FFDB9C" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_F03C8C87FF1C212F8277922042FDDDB8" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_B76F74681A1DA7AEA14F922042FE8329" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_F03C8C87FF1C212F8277922042FDDDB8" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_B76F74681A1DA7AEA14F922042FE8329" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReceivableTypeDomain" xlink:label="loc_us-gaap_ReceivableTypeDomain_2C2D70D4E7246D34EFEB922042FFE685_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_B76F74681A1DA7AEA14F922042FE8329" xlink:to="loc_us-gaap_ReceivableTypeDomain_2C2D70D4E7246D34EFEB922042FFE685_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReceivableTypeDomain" xlink:label="loc_us-gaap_ReceivableTypeDomain_2C2D70D4E7246D34EFEB922042FFE685" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_B76F74681A1DA7AEA14F922042FE8329" xlink:to="loc_us-gaap_ReceivableTypeDomain_2C2D70D4E7246D34EFEB922042FFE685" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_CardSettlementsDueFromMerchantsMember" xlink:label="loc_prth_CardSettlementsDueFromMerchantsMember_61B6AE383D690309E7B3922042FF1E9D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_2C2D70D4E7246D34EFEB922042FFE685" xlink:to="loc_prth_CardSettlementsDueFromMerchantsMember_61B6AE383D690309E7B3922042FF1E9D" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_CardSettlementsDueFromProcessorsMember" xlink:label="loc_prth_CardSettlementsDueFromProcessorsMember_4DE272A276B6CD67F033922042FFA06D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_2C2D70D4E7246D34EFEB922042FFE685" xlink:to="loc_prth_CardSettlementsDueFromProcessorsMember_4DE272A276B6CD67F033922042FFA06D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_687ABDFD7CC8597A037D922042FD288F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_F03C8C87FF1C212F8277922042FDDDB8" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_687ABDFD7CC8597A037D922042FD288F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_FDF18C3366C0DFBAAFF6922042FE13F8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_687ABDFD7CC8597A037D922042FD288F" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_FDF18C3366C0DFBAAFF6922042FE13F8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_FDF18C3366C0DFBAAFF6922042FE13F8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_687ABDFD7CC8597A037D922042FD288F" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_FDF18C3366C0DFBAAFF6922042FE13F8" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_CardSettlementsDueToMerchantsMember" xlink:label="loc_prth_CardSettlementsDueToMerchantsMember_E69C24422D5609F8CA19922042FEAFAA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_FDF18C3366C0DFBAAFF6922042FE13F8" xlink:to="loc_prth_CardSettlementsDueToMerchantsMember_E69C24422D5609F8CA19922042FEAFAA" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_DueToACHPayeesMember" xlink:label="loc_prth_DueToACHPayeesMember_CBF2A21FDD84D9F5CAAB922042FE2E35" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_FDF18C3366C0DFBAAFF6922042FE13F8" xlink:to="loc_prth_DueToACHPayeesMember_CBF2A21FDD84D9F5CAAB922042FE2E35" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_MerchantReservesHeldBySponsorBanks" xlink:label="loc_prth_MerchantReservesHeldBySponsorBanks_65A897A40194BA908BCD922042FF9252" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_15B12D109886DC83DD6C922042FFDB9C" xlink:to="loc_prth_MerchantReservesHeldBySponsorBanks_65A897A40194BA908BCD922042FF9252" xlink:type="arc" />
    <link:loc xlink:href="prth-20190930.xsd#prth_SettlementAssetsEstimatedShortfall" xlink:label="loc_prth_SettlementAssetsEstimatedShortfall_EE622FF3B5EBBFD4B1F6922043008DD3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_15B12D109886DC83DD6C922042FFDB9C" xlink:to="loc_prth_SettlementAssetsEstimatedShortfall_EE622FF3B5EBBFD4B1F6922043008DD3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SettlementAssetsCurrent" xlink:label="loc_us-gaap_SettlementAssetsCurrent_EF7D743FF25390513A729220430011A9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_15B12D109886DC83DD6C922042FFDB9C" xlink:to="loc_us-gaap_SettlementAssetsCurrent_EF7D743FF25390513A729220430011A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SettlementLiabilitiesCurrent" xlink:label="loc_us-gaap_SettlementLiabilitiesCurrent_863C1BDCBFB205476A1C92204300DB70" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_15B12D109886DC83DD6C922042FFDB9C" xlink:to="loc_us-gaap_SettlementLiabilitiesCurrent_863C1BDCBFB205476A1C92204300DB70" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://miacquisitions.com/role/SettlementAssetsAndObligationsTables" xlink:type="extended" />
</link:linkbase>
