noun, plural wea·sels, (especially collectively) wea·sel.
- any small carnivore of the genus Mustela, of the family Mustelidae, having a long, slender body and feeding chiefly on small rodents.
- any of various similar animals of the family Mustelidae.
- a cunning, sneaky person.
- a tracked vehicle resembling a tractor, used in snow.
- Slang. an informer; stool pigeon.