hippopotamus, hippo, river horse, Hippopotamus amphibius
['hatchet', 'shower cap', 'spoonbill', 'acorn', 'killer whale, killer, orca, grampus, sea wolf, Orcinus orca', 'siamang, Hylobates syndactylus, Symphalangus syndactylus', 'buckeye, horse chestnut, conker']