lavatorium

noun4

1. •
   (rare) A washroom or -place.
2. •
   (rare) Particularly, (architecture) the communal washing area in a monastery.
3. •
   (rare) A lavatory.

   • A visit to the toilet proves embarrassing. Luke directs me to ‘the lavatorium’, a room with a long wooden bench that has four seats with holes the size of dinner plates. — 2015
4. •
   (rare, historical) An ancient Roman lavatory.

   • They say that because he’s missing so much of his liver, he can’t digest his food like normal people and hasn’t been to the lavatorium in years. They say he’s gonna blow like a volcano. — 2008