Quadruped

A quadruped, traditionally, means an animal which walks on four legs. This is mainly to distinguish them from bipeds, which walk on two.

Quadruped and furry
The furry community has retained this terminology to distinguish morphic and nonmorphic animals, and while there are some other species which could fit the definition (taurs, which have four walking legs, for example) it is rarely applied to them.

Quad, quaddie, and "four on the floor" are other, informal names used to describe a quadruped.