Theatre or theater? Words like caliber, somber and liter were at one point spelt calibre, sombre and litre even when used in English. This was installed to protect the French etymology of the word. Times have changed, but the word Theat(-re,-er) is the only one still debated. People in the theat(-re,-er) world tend to spell it theatre and those who are not might spell it theater. Some people say that the word theat(-re,-er) is the very thing that is holding people back from coming to the theat(-re,-er).