mutt

Short definition from Wiktionary

Noun

1. 1
   A mongrel dog (or sometimes cat); an animal of mixed breed or uncertain origin.
2. 2
   A person of mixed racial or ethnic ancestry.
3. 3
   An idiot, a stupid person.
4. 4
   A person from the United States, in reference to sense 2.
5. 5
   The snowy sheathbill.
6. 6
   Alternative form of matha.