1) Anus 2) Arsehole 3) Ass 4) Buns 5) Buttocks 6) Derriere 7) Fanny 8) Hindquarters 9) Keister 10) Nates 11) Prat 12) Tooshie 13) Tush 1) Backside 2) Bath bottom 3) Bath butt 4) Behind 5) Body part 6) Bottom 7) Bottom of the Tube 8) Bottom, abroad 9) British bottom 10) British bum 11) British derri�re 12) British sitter 13) Buns 14) Butt 15) Buttocks 16) Can at a pub 17) Canterbury can 18) Cheeky part of a Brit 19) Chelsea buns 20) Derby derriere 
• (n.) The buttocks, or hind part of an animal; the posteriors; the fundament; the bottom.
Arse noun [ Anglo-Saxon ears ; ærs ; akin to Old High German ars . German arsch , Dutch aars , Swedish ars , Danish arts , Greek ... (cf. ... tail).] The buttocks, or hind part of an animal; the posteriors; the fundament; the bottom. 
ass
Arse is British slang for the buttocks or anus.
ass (defs. 1, 2).