Old English ærs, of Germanic origin; related to Dutch aars and German Arsch.

• Like bum, arse was not originally a rude slang word. It dates back to before 1000 in English, and is connected to various old German and Scandinavian forms that were probably linked to Greek orros ‘the rump or bottom’. Arse was perfectly respectable until the 17th century. To go arse over tip (the original form, rather than tit) and not know your arse from your elbow are first found in the early 20th century. My arse! as a derisive comment is first recorded in the 1920s, though all these expressions are probably older. The American spelling is ass, which is nothing to do with ass meaning ‘donkey’. The latter is from an Old English word that is related to easel and goes back to Latin asinus, as in asinine (Late Middle English) or stupid. See also wheat

Old English ærs, of Germanic origin; related to Dutch aars and German Arsch.