1. A fabulous creature, half horse and half fish, represented in classic mythology as driven by sea dogs or ridden by the Nereids. It is also depicted in heraldry. See Hippocampus. [ 1913 Webster ]
2. (Zool.) (a) The walrus. (b) Any fish of the genus Hippocampus. [ 1913 Webster ]
☞ In a passage of Dryden's, the word is supposed to refer to the hippopotamus. [ 1913 Webster ]