Ass
Part of speech: noun
Definition: A beast of burden, particularly a donkey. A jerk; a mean or rude person. A stupid person (passing into Etymology 2) buttocks Sex. anus. Used in similes to express something bad or unpleasant. Any of several species of horse-like animals, especially Equus asinus, the domesticated of which are used as beasts of burden. Self.
Arse
Part of speech: noun
Definition: (not used in US, Canada) buttocks; the back of anything.(not used in US, Canada) stupid, mean or despicable person.
Part of speech: verb
Definition: To be silly, act stupid or mess around.To have the effort to do something, to be bothered.