The hippopotamus (Hippopotamus amphibius) or hippo (Greek: , hippopotamos, from , hippos, 'horse' and , potamos, 'river') is a large, mostly plant-eating African mammal, one of only two extant species in the family Hippopotamidae (the other being the Pygmy Hippopotamus). It is the heaviest extant artiodactyl, despite being significantly shorter than the Giraffe.