The hippopotamus (Hippopotamus amphibius) (/ˌhɪpəˈpɒtəməs/; pl.: hippopotamuses; also shortened to hippo (pl.: hippos), further qualified as the common hippopotamus, Nile hippopotamus, or river hippopotamus, is a large semiaquatic mammal native to sub-Saharan Africa. It is one of only two extant species in the family Hippopotamidae, the other being the pygmy hippopotamus (Choeropsis liberiensis or Hexaprotodon liberiensis). Its name comes from the ancient Greek for "river horse" (ἱπποπόταμος).