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
See hippopotamus in American Heritage Dictionary 4
(hĭpˌə-pŏtˈə-məs)
nounpl.hip·po·pot·a·mus·es or hip·po·pot·a·mi(-mīˌ)
A large, chiefly aquatic African herbivorous mammal (Hippopotamus amphibius) having thick, dark, almost hairless skin, short legs with four toes, and a broad, wide-mouthed muzzle. Also called river horse.