Hippopotamus rhymes with:
artemus, anonymous, artemus, autonomous, blasphemous, clackamas, infamous, magnanimous, monogamous, polygamous, pusillanimous, synonymous, thalamus, unanimous, venomous
artemus, anonymous, artemus, autonomous, blasphemous, clackamas, infamous, magnanimous, monogamous, polygamous, pusillanimous, synonymous, thalamus, unanimous, venomous