Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† hippŏpŏtămus, i, m., = ἱπποπόταμος, a river-horse, hippopotamus, Plin. 8, 25, 39, § 95; Mel. 1, 9, 3; Amm. 22, 15.