Lavatory vs. Washroom vs. Bathroom vs. Restroom

A wash basin

A room with a toilet (sewer or septic tank compatible) and wash basin

A room with a toilet (sewer or septic tank compatible), sink (plumbling compatible), and bath (or shower)

A room with a toilet (sewer or septic tank compatible) and sink (plumbling compatible) (euphamism for bathroom)

The term “restroom” derived from up-scale restaurants, theaters, and performing facilities in the early 1900s through to the middle of the century providing comfortable chairs or sofas, located within or in a room directly adjacent to the actual toilet and sink facilities.

(pretty self-explanatory)

A seat over a hole (cesspit) used to collect waste

A building with a seat over a hole (cesspit) used to collect waste