any of a family (Hippopotamyidae) of large, plant-eating, artiodactylous mammals with a heavy, thick-skinned, almost hairless body and short legs: they live chiefly in or near rivers in Africa
Origin:
L < Gr hippopotamos, lit., river horse < hippos (see hippo-) + potamos, river, orig., that which goes down < IE base *pet-, to fall, fly > feather, Gr pteryx, wing