Real Dictionary

bobtail in American English
a short tail or one cut short
to dock the tail of
adjective: having a bobtail
noun: a short or docked tail
transitive verb: to cut short the tail of; dock, often by cutting a muscle in a horse's tail to make it stand erect

bobtail in British English
to dock the tail of
adjective: having the tail cut short
noun: a docked or diminutive tail