Why is it called a restroom, anyway?
Why would anyone want to rest in a room with a toilet? Or why would anyone move a toilet into a room of rest? And toilets used to be smellier than they are now, I'm sure. Who was the idiot who thought of this?
Of course no one wants to rest in the room containing the toilet; restroom is an obvious euphemism. Interestingly, English (like some other languages) can express the "toilet-room" concept only via indirect terms like this. The French are more straightforward – pissoir means “place to piss” – but English has no similarly unadorned word aside from shithouse, which is not exactly usable in most conversation. Cecil addressed this phenomenon back in 1985, but now seems like a fine opportunity to work our way through the long list of toilet euphemisms and their origins, so far as is known. We’ll take them alphabetically:
John. One of the the most common American euphemisms; Cecil's also discussed this one in some depth. In 1735 a Harvard regulation referred to a toilet enclosure using the term cuzjohn, an abbreviation of “cousin John.” Even earlier terms included jakes (from the late 1530s, meaning a chamber pot) and Jack’s house or Jack’s place. By the 1800s there were several different proper names in use: the Joe, the Jane, the Fred, Miss White’s, or the Widow Jones. Of interest: john also, of course, means a prostitute’s client (since at least 1906) but in the 1800s meant policeman – an abbreviation for "John Darm," a pun on the French gendarme.
Ladies' room and gentlemen’s room. Probably the most polite of the several designations for public toilets; also seen as just ladies and gents, boys’ room and girls’ room, and other sex-differentiated variations. (Crime-caper author Donald Westlake in one novel describes a NYC bar that uses “Pointers” and “Setters.") The terms nowadays tend to be the less formal (and less class-conscious) women’s room and men’s room.
Latrine. Usually used to mean a military toilet. Via French, ultimately from the Latin lavare meaning "to wash." The OED cites 1642 as the earliest use found in English.
Lavatory. Also from the Latin lavare, also via French. Middle Latin has lavatorium meaning washbasin, or a washing room in a monastery or convent. Thus since the 1300s a lavatory was a place to wash one’s hands. It therefore became a natural euphemism for the place where one does things that require hand washing afterwards; this development seemingly dates from the mid- to late 1800s. The Brits sometimes abbreviate it, calling it the lav or the lavvy. Like toilet, lavatory can mean the room or the device.
Loo. This is a British euphemism that’s been taken up by other English speakers. Cecil addressed this earlier, in his column on the john, but we include it here for completeness's sake. Its origin isn't known for sure, although it's probably just from the French l’eau, meaning “water.” Another possible origin is bordalou, a portable ladies’ privy looking something like a gravy boat and carried in a muff. There was also a medieval expression gardyloo, probably derived from the French guardez l’eau, meaning “watch out for the water!” – which is what one might yell to alert passers-by when one was tossing slops out the window. Another possible origin for loo, although less likely, is from the French lieu meaning “place,” as in lieu d’aisance, a French term for toilet. There are also highly improbable stories of loo's arising from the name of a hated countess Louise or from the battle of Waterloo. However, the OED does cite some wordplay from Ulysses (1922) in which Joyce juxtaposes “Waterloo" and "watercloset.”
Restroom. Originally meaning a public toilet, this seems to be of American origin, with the earliest usages found around 1900. It’s an extremely common usage, and also one of the vaguest. Rest of course has a number of meanings, but this is probably in the sense of "repose" or "refreshing oneself." A slight variation is retiring room, a lovely upper-class Briticism from the 1930s.
Toilet. This too is ultimately a euphemism, from the French toilette meaning “dressing room,” from toile meaning “cloth.” In the 17th century, the toilet was the process of getting dressed – powdering one's wig and so forth. In the 18th century, a toilet call was a social interaction in which a lady received visitors while she was in the last stages of performing her toilet. By the 19th century, we have toilet articles, toilet pail (a bucket to hold slops), and toilet paper (used for shaving, hair curling, etc). The term toilet room seems to have been American in origin, from the late 1800s, and thence abbreviated to simply toilet. Again, the word can mean both the room and the device.
Wash room. An Americanism from around 1850. “I was washing my hands” was a polite way to avoid describing what one was doing in there for so long. The term arose around the same time that lavatory was being used for the same place.
Water closet or WC. British. The water closet was the room with the toilet, whereas the bathroom was the room with the bathtub. (Don’t get me started on how disgusting it is that we now typically combine these.) Water closets date from the mid-1700s but didn’t become common until somewhat later. In 1814 John Phair wrote a book called Observations on the Principle and Construction of Water-Closets, Chimneys, and Bell-Hanging (not such a weird combination if you consider that bell wires were usually hung along water-closet pipes). By the late 1850s it was very modern and fashionable and convenient in England to have an indoor water closet, and indoor plumbing became the rage. The WC was often located off the landing halfway up the stairs from the first to the second story (hence the alternate term “halfway house").
Some others, not all of them commonly used today:
• Can or cabinet. Possibly originally referring to the toilet with a replaceable container or can beneath the seat. Dates to roughly 1914.
• Comfort station or comfort room. These arose around 1900. In 1978 New York City implemented “canine comfort stations” in response to the dog poop problem.
• The Facilities. A nice, formal, polite way around the problem.
• Necessary room or necessaries. Used in the early 1700s, obviously long before indoor plumbing. There were also “necessary houses," "necessary stools," etc.
• Outhouse. A smaller building near the dwelling house and “used for some subsidiary purpose,” according to the OED of 1904, “e.g., a stable, barn, washhouse, toolhouse, or the like.” I guess “or the like” is itself a euphemism.
• Privy. Usually refers to a separate structure, an outdoor toilet; in use as of the 1300s. The term generally meant "something private, intimate, or concealed."
• Throne. Originally used to refer to a chamber pot, and thence to a toilet. As of 1922 people were referring to the room containing the throne as the “throne room." However, the antecedents are ancient: I came across a reference in the Talmud, certainly written before 600 AD, describing someone going to the "house of the chair."
Finally, the powder room was originally the place on a ship where the ammunition and gunpowder were stored. However, in the era of makeup, it was the place a woman went to “powder her nose.” This became a way to describe what Hugh Rawson calls “a private errand involving neither powder nor nose” The OED locates the earliest published usage of this phrase in 1941. Rawson also quotes from Edward Albee's Who’s Afraid of Virginia Woolf? (1962):
HONEY: I want to… put some powder on my nose.
GEORGE: Martha, won’t you show her where we keep the euphemism?
My own personal anecdote: At age seven or so, our daughter told us, very seriously, that the dog had “powdered his nose on the living room carpet.” It took us a moment or two to figure out what the hell she meant.