pachydermata
Pach`y*der"ma*ta, n. pl. [NL., fr. Gr. thick-skinned; pachy`s thick + skin.] (Zoöl.) Defn: A group of hoofed mammals distinguished for the thickness of their skins, including the elephant, hippopotamus, rhinoceros, tapir, horse, and hog. It is now considered an artificial group.