Pach`y*der"ma*ta (?), n. pl. [NL., fr. Gr. &?; thick-skinned; pachy`s thick + &?; skin.] (Zoöl.)
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.
© Webster 1913