Arse and Buttocks

Arse noun - The fleshy part of the human body that you sit on.

Buttocks is a synonym for arse in bottom topic. In some cases you can use "Buttocks" instead a noun "Arse", when it comes to topics like tail, backside.

Buttocks noun - The part of the body upon which someone sits.

Arse is a synonym for buttocks (British) in bottom topic. You can use "Arse" instead a noun "Buttocks", if it concerns topics such as tail, backside, vulgar slang.