Hippopotamus
The word "hippopotamus" comes from the ancient Greek , hippopotamos, from , hippos, "horse" and , potamos, which means "river". So, "hippopotamus" means "horse of the river". More than one hippopotamus are called hippopotami, and 'hippopotamuses' or 'hippos' is also used. Hippopotami are social. About 30 hippos live together in groups. A male hippopotamus is known as a bull. A female hippopotamus is called a cow and a baby hippo is called a calf. The species is also known as the common hippopotamus or the Nile hippopotamus.