noun

a person’s regular female companion with whom they have a romantic or sexual relationship.

he lives with his girlfriend

partner,lover,significant other,girl,woman,loved one,love,beloved,darling,dearest,sweetheart,live-in lover,cohabitee,common-law wife,fiancée,inamorata,querida,other half,better half,baby,bae,gf,date,steady,bird,mot,dona,bibi,fancy woman,lady,lady friend,lady love,young lady,betrothed,squeeze,leman