arse definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
Brit. the buttocks; ass: now a vulgar term
Origin: Middle English ars ; from Old English ears, ærs ; from Indo-European base an unverified form orsos from source Classical Greek oura, tail
arse definition by American Heritage Dictionary
noun Chiefly British Slang
Variant of ass2.