If two people are cohabiting, they are living together and have a sexual relationship, but are not married. In Italy people hardly ever cohabit The dentist left his wife of 15 years and openly cohabited with his receptionist Any solicitor will tell you, if you're cohabiting and the man leaves you, you haven't got a leg to stand on. + cohabitation co·habi·ta·tion The decline in marriage has been offset by a rise in cohabitation. to live with another person and have a sexual relationship with them without being married (cohabitare, from co- ( CO-) + habitare ( HABITATION))