<?xml version="1.0" encoding="US-ASCII"?>
<!-- Generated by Broadridge Transform (tm) - http://www.broadridge.com -->
<!-- Created: Fri Aug 07 13:30:27 UTC 2026 -->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:xbrldt="http://xbrl.org/2005/xbrldt">
  <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/spac/2026/spac-2026.xsd#SponsorsAffiliatesOrPromotersOnly" roleURI="http://xbrl.sec.gov/spac/role/SponsorsAffiliateOrPromotersOnly"/>
  <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/spac/2026/spac-2026.xsd#SecurityClassesOnly" roleURI="http://xbrl.sec.gov/spac/role/SecurityClassesOnly"/>
  <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/spac/2026/spac-2026.xsd#DilutionSourcesOnly" roleURI="http://xbrl.sec.gov/spac/role/DilutionSourcesOnly"/>
  <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/spac/2026/spac-2026.xsd#CompensationNaturesOnly" roleURI="http://xbrl.sec.gov/spac/role/CompensationNaturesOnly"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all"/>
  <definitionLink xlink:role="http://xbrl.sec.gov/spac/role/SponsorsAffiliateOrPromotersOnly" xlink:type="extended">
    <loc xlink:type="locator" xlink:label="spac_AllSpacSponsorsAffiliatesOrPromotersMember" xlink:href="https://xbrl.sec.gov/spac/2026/spac-2026.xsd#spac_AllSpacSponsorsAffiliatesOrPromotersMember"/>
    <loc xlink:type="locator" xlink:label="port_SouthportAcquisitionSponsorIILLCMember" xlink:href="port-20260807.xsd#port_SouthportAcquisitionSponsorIILLCMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSpacSponsorsAffiliatesOrPromotersMember" xlink:to="port_SouthportAcquisitionSponsorIILLCMember" order="13" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_CohenCompanyCapitalMarketsMember" xlink:href="port-20260807.xsd#port_CohenCompanyCapitalMarketsMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSpacSponsorsAffiliatesOrPromotersMember" xlink:to="port_CohenCompanyCapitalMarketsMember" order="14" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_SponsorMember" xlink:href="port-20260807.xsd#port_SponsorMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSpacSponsorsAffiliatesOrPromotersMember" xlink:to="port_SponsorMember" order="15" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:role="http://xbrl.sec.gov/spac/role/SecurityClassesOnly" xlink:type="extended">
    <loc xlink:type="locator" xlink:label="spac_AllSecurityClassesMember" xlink:href="https://xbrl.sec.gov/spac/2026/spac-2026.xsd#spac_AllSecurityClassesMember"/>
    <loc xlink:type="locator" xlink:label="port_OfferingPriceOf10PointZeroPerUnitMember" xlink:href="port-20260807.xsd#port_OfferingPriceOf10PointZeroPerUnitMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSecurityClassesMember" xlink:to="port_OfferingPriceOf10PointZeroPerUnitMember" order="17" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_NetProceedsFromThisOfferingAndTheSaleOfThePlacementSharesMember" xlink:href="port-20260807.xsd#port_NetProceedsFromThisOfferingAndTheSaleOfThePlacementSharesMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSecurityClassesMember" xlink:to="port_NetProceedsFromThisOfferingAndTheSaleOfThePlacementSharesMember" order="18" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_PlusOfferingCostsAccruedForOrPaidInAdvanceExcludedFromTangibleBookValueMember" xlink:href="port-20260807.xsd#port_PlusOfferingCostsAccruedForOrPaidInAdvanceExcludedFromTangibleBookValueMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSecurityClassesMember" xlink:to="port_PlusOfferingCostsAccruedForOrPaidInAdvanceExcludedFromTangibleBookValueMember" order="19" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_LessDeferredUnderwritingCommissionsMember" xlink:href="port-20260807.xsd#port_LessDeferredUnderwritingCommissionsMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSecurityClassesMember" xlink:to="port_LessDeferredUnderwritingCommissionsMember" order="20" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_LessOverallotmentLiabilityMember" xlink:href="port-20260807.xsd#port_LessOverallotmentLiabilityMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSecurityClassesMember" xlink:to="port_LessOverallotmentLiabilityMember" order="21" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_LessAmountsPaidForRedemptionsMember" xlink:href="port-20260807.xsd#port_LessAmountsPaidForRedemptionsMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSecurityClassesMember" xlink:to="port_LessAmountsPaidForRedemptionsMember" order="22" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_OrdinarySharesForfeitedIfOverallotmentIsNotExercisedMember" xlink:href="port-20260807.xsd#port_OrdinarySharesForfeitedIfOverallotmentIsNotExercisedMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSecurityClassesMember" xlink:to="port_OrdinarySharesForfeitedIfOverallotmentIsNotExercisedMember" order="23" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_OrdinarySharesOfferedMember" xlink:href="port-20260807.xsd#port_OrdinarySharesOfferedMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSecurityClassesMember" xlink:to="port_OrdinarySharesOfferedMember" order="24" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_PrivatePlacementSharesMember" xlink:href="port-20260807.xsd#port_PrivatePlacementSharesMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSecurityClassesMember" xlink:to="port_PrivatePlacementSharesMember" order="25" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_LessOrdinarySharesRedeemedMember" xlink:href="port-20260807.xsd#port_LessOrdinarySharesRedeemedMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllSecurityClassesMember" xlink:to="port_LessOrdinarySharesRedeemedMember" order="26" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:role="http://xbrl.sec.gov/spac/role/DilutionSourcesOnly" xlink:type="extended">
    <loc xlink:type="locator" xlink:label="spac_AllDilutionSourcesMember" xlink:href="https://xbrl.sec.gov/spac/2026/spac-2026.xsd#spac_AllDilutionSourcesMember"/>
    <loc xlink:type="locator" xlink:label="port_WithoutOverAllotmentMember" xlink:href="port-20260807.xsd#port_WithoutOverAllotmentMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllDilutionSourcesMember" xlink:to="port_WithoutOverAllotmentMember" order="23" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_WithOverAllotmentMember" xlink:href="port-20260807.xsd#port_WithOverAllotmentMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllDilutionSourcesMember" xlink:to="port_WithOverAllotmentMember" order="24" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:role="http://xbrl.sec.gov/spac/role/CompensationNaturesOnly" xlink:type="extended">
    <loc xlink:type="locator" xlink:label="spac_AllCompensationNaturesMember" xlink:href="https://xbrl.sec.gov/spac/2026/spac-2026.xsd#spac_AllCompensationNaturesMember"/>
    <loc xlink:type="locator" xlink:label="port_ClassBOrdinarySharesMember" xlink:href="port-20260807.xsd#port_ClassBOrdinarySharesMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllCompensationNaturesMember" xlink:to="port_ClassBOrdinarySharesMember" order="17" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="port_PrivateClassAOrdinarySharesMember" xlink:href="port-20260807.xsd#port_PrivateClassAOrdinarySharesMember"/>
<!-- [WMV7][VdDCKEfXSmbgMdSQ3sH1lKwGCL90H3CU8VuaNDULl+jdEdlBopaSYzJmV+hHIprlqa4tpx3/0WW3WM/PU7vCo/yLyw62l6qj24x3ypDBQzEkwRJltvK3QVkjfiPr6UESTdytBd08djg6jDqlaQYNcJNBXPJDjQYLsdLg7aDZx3hJ+YVJIghXE12TtWLChTJmfxQBdOjEZkEXvTmN/N8Txfk5kARTSIDM/4qy0IFYNVYdIQGb+AjRk2S0Z+bAevF2r3UnzayqmKo1mnMshtjnP0UICIcO0vE7yu5z+Qwy2Nd+RgVdAQHvBAj+sP1tR4bCiC4gszWsUxpLk0iuOmrYiKbIaKojf8ObBFgvs6kpYHkFYLE6ZBDNLkN5ng6Id7HoojnUJjhvXHfAVdh1] CSR-->
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="spac_AllCompensationNaturesMember" xlink:to="port_PrivateClassAOrdinarySharesMember" order="18" xbrldt:closed="true"/>
  </definitionLink>
</linkbase>
