Pachydermata

‖n. pl. [ NL., fr. Gr. pachy`dermos thick-skinned; pachy`s thick + de`rma skin. ] (Zool.) A group of hoofed mammals distinguished for the thickness of their skins, including the elephant, hippopotamus, rhinoceros, tapir, horse, and hog; the pachyderms. It is now considered an artificial group. [ 1913 Webster ]