Origin: L rodens, present participle of rodere, to gnaw: see rat
any of a very large order (Rodentia) of gnawing mammals, including rats, mice, squirrels, and beavers, characterized by constantly growing incisors adapted for gnawing or nibbling; esp., in popular usage, a rat or mouse
Any of various very numerous, mostly small mammals of the order Rodentia, having large front teeth used for gnawing. The teeth grow throughout the animal's life, and are kept from getting too long by gnawing. Rodents make up about half the living species of mammals, and include rats, mice, beavers, squirrels, lemmings, shrews, and hamsters.