Any of an order (Rodentia) of relatively small gnawing mammals (as a mouse, a squirrel, or a beaver) that have in both jaws a single pair of teeth with a chisel-shaped edge.

an order of gnawing or nibbling mammals which includes rats, mice, squirrels, gophers, beavers, porcupines and hamsters

a family of mammals which have large front teeth used for gnawing

The gnawing Mammalia, such as the Rats, Rabbits, and Squirrels. They are especially characterised by the possession of a single pair of chisel-like cutting teeth in each jaw, between which and the grinding teeth there is a great gap. 185