From Longman Dictionary of Contemporary Englishrest roomˈrest room noun [countable] American EnglishDL a room with a toilet in a place such as a restaurant or cinema SYN toilet British English
Examples from the Corpus
rest room• When she went into the rest room she sat down for a minute while waiting for Peggy to come out of the lavatory.• As he finished washing his hands, he heard laughter on the other side of the rest room wall.• We looked over the snacks at Pembina and used the rest room. 