The definition of a mutt is a dog that does not have a pedigree.
A mixed breed dog you get at the pound is an example of a mutt.
- Slang a stupid or incompetent person
- Informal a dog of mixed breed; mongrel
Origin of muttprobably contr. ; from muttonhead
- A mongrel dog.
- A stupid person; a dolt.
Origin of muttShort for muttonhead.