(Science: zoology) An order of mammals having two (rarely four) large incisor teeth in each jaw, distant from the molar teeth. The rats, squirrels, rabbits, marmots, and beavers belong to this order.
The incisor teeth are long, curved, and strongly enameled on the outside, so as to keep a cutting edge. They have a persistent pulp and grow continuously.
Origin: NL. See Rodent.