the.com/lavatory

means A room or fixture for washing up and relieving yourself — the formal word for a bathroom or toilet.

from From Latin lavare, 'to wash,' via lavatorium, 'a place for washing.' It originally meant exactly that — a washing area, often with basins for hands and face — and only gradually slid in meaning to cover the toilet itself, as Victorian-era euphemism piled on euphemism to avoid saying the blunter word. So the posh name actually started honest, about washing, before being drafted into polite evasion.