a dog, cat or horse with a tail that has been cut short 短尾狗（或猫、马） a tail that has been cut short 截短的尾巴；短尾
Word Originmid 16th cent.: probably from bob ‘ the short hairstyle’ + tail. It was originally recorded as a humorous term for a kind of broad-headed arrow, probably because it looked as though it had been cut short.