restroom
n. countable A2 Elementary US //ˈɹɛsˌtɹum// UK //ɹˈɛstɹuːm// re·stroom
n. a room in a public building with a toilet and a sink for washing your hands.
n. a public room containing a toilet and sink facilities. Primarily used in North American English as a polite or formal alternative to 'toilet'.
Excuse me, where is the nearest restroom?
The restaurant manager ensured the restroom was cleaned every hour to maintain a high standard for customers.
From rest + room, from an earlier sense of "breakroom".
Usage
Commonly used in North American English; in British English, 'toilet' or 'loo' is more frequent.