My father usually called that little room the “loo,” a word I long associated with Waterloo. It actually comes from the French phrase gardez l’eau, a warning yelled by the servant when waste water was dumped out of the window. “Watch out for the water!” the servant would yell. It wasn’t always water.
In colonial India, they had the “thunder box,” which was a wooden box with a hole in the top and a lid over the hole. It was secured to the outside wall, and there was a hole in the wall through which a servant could reach and remove the ceramic pot. There was a bolt on the lid of the box to prevent animals or a (very small) burglar from getting into the house.
The great stone castles of medieval Europe also had toilets. These were small, private chambers that usually emptied into the moat and the smell in the chamber was so toxic that it killed moths and other insects. This made it a handy place to store heavy winter clothing, and so the room came to be called a garde robe, another French phrase that became the English “wardrobe.”
My brothers and I usually called the room the “lav,” which is short for “lavatory,” which comes from the Latin lavare, “to wash.” My sisters preferred to call it the “toilet,” which was originally the French toilette and meant a vanity table in a dressing room. Toilet sounds nicer than other names for what today we usually call the “bathroom,” whether or not there is a bathtub in the room.
Now and then my father would call it the “jakes.” It was some years before I learned that this word came from the French name Jacques, or John in English. Being named John, I didn’t particularly like that association of words. But worse was to follow. When I moved to North America, I discovered that many people actually call the bathroom the john. (Note that unlike my name, it’s not capitalized.) In my opinion, anything is better than “the john.” Perhaps we could revive the almost vanished term WC for “water closet”?