ἱπποπόταμος

A. hippopotamus, Dsc. 2.23, Gal. 14.241, Dam. Isid. 98:—also ἱππο‐ποτάμις (for ‐ποτάμιος), ὁ, POxy. 1220.21 (iii A.D.).
Liddell, Scott & Jones
A Greek-English Lexicon, 1940
An open-access project