If two people are cohabiting, they are living together and have a sexual relationship, but are not married.
例句
In Italy people hardly ever cohabit...在意大利,很少有人未婚同居。The dentist left his wife of 15 years and openly cohabited with his receptionist...那个牙医离开了和他生活了15年的妻子,与自己诊所的接待小姐公开同居。
英汉词典释义
n.
同居
the cessation of cohabitation of man and wife.一个男人和他妻子同居生活的结束