A woman with an attractive body but an ugly head.
Person A: Whoa, she's hot.
Person B: No she's not. She's a buterhead.
Person A: What do you mean?
Person B: Everything is hot about her, but-her-head
used to describe a hot chick from the neck down. (as in...everything but her head)
She's a buterhead. She looked great from behind, but she was a buterhead.