From WordNet (r) 2.0 (August 2003) [wn]:
hippopotamus
n : massive thick-skinned herbivorous animal living in or around
rivers of tropical Africa [syn: hippo, river horse,
Hippopotamus amphibius]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Hippopotamus \Hip`po*pot"a*mus\, n.; pl. E. Hippopotamuses, L.
Hippopotami. [L., from Gr.?; "i`ppos horse + ? river. Cf.
Equine.] (Zool.)
A large, amphibious, herbivorous mammal ({Hippopotamus
amphibius}), common in the rivers of tropical Africa. It is
allied to the hogs, and has a very thick, naked skin, a thick
and square head, a very large muzzle, small eyes and ears,
thick and heavy body, and short legs. It is supposed to be
the behemoth of the Bible. Called also zeekoe, and {river
horse}. A smaller species (Hippopotamus Liberiencis)
inhabits Western Africa.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
pachyderm \pach"y*derm\ (p[a^]k"[i^]*d[~e]rm), n. [Cf. F.
pachyderme.] (Zool.)
Any of various nonruminant hoofed mammals having very thick
skin, including the elephant, rhinoceros, and
hippopotamus, one of the Pachydermata.
[WordNet 1.5 + 1913 Webster]