Restroom is a euphemism for a public toilet, in a publicly accessible location, or less frequently a toilet room, in a private residence. Different dialects use “bathroom” and “restroom” (American English), “bathroom” (usually includes a bathtub or shower) and “washroom” (just toilet and sink) (Canadian English), and “WC” (an initialism for “water closet”), “lavatory” and its abbreviation “lav” (British English).
The term restroom derived from the fact that in early 1900s through to the middle of the century up-scale restaurants, theatres and performing facilities would often have comfortable chairs or sofas located within or in a room directly adjacent to the actual toilet and sink facilities, something which can be seen in some movies of the time period. An example of this is the description of a “movie palace” which was opening in 1921 which was described as including ” … a rest-room for the fair sex and a lounging room for the sterner sex … off these rooms are the toilets.”
Euphemisms for the toilet that bear no direct reference to the activities of urination and defecation are ubiquitous in modern Western languages, reflecting a general attitude of unspeakability about such bodily function. As the euphemism, “restroom” has come to be associated with the actual function of the toilet, further euphemisms such as “powder room” and “lounge” have been constructed to avoid using the word “restroom” itself.
Use of the euphemism has caused confusion when conveyed to visitors from other cultures, or misapplied by speakers from other cultures. For example, in the 1970s the official Xinhua News Agency of China published an English-language story stating that the vice-premier had met with guests in the Beijing International Airport restroom, by which the authors meant a lobby.