cohabit

Universal Words verb [V] ~ (with sb) (formal) (usually of a man and a woman) to live together and have a sexual relationship without being married: cohabiting couples * She refused to cohabit with him before the wedding. cohabitation noun [U]: There have been great changes in the patterns of marriage, divorce and cohabitation. * (figurative) a period of cohabitation between a conservative government and a socialist president