1. a room, building, or cubicle containing a toilet or toilets: "he locked himself in the downstairs lavatory"
▪ a flush toilet: "she flushed the lavatory"
▪ a sink or washbasin in a bathroom or toilet.
Word Originlate Middle English: from late Latin lavatorium ‘place for washing’, from Latin lavare ‘to wash’. The word originally denoted something in which to wash, such as a bath or piscina, later (mid 17th century) a room with washing facilities; the current sense dates from the 19th century.