Hippopotamus literally translates to river horse in Greek

Ancient naming conventions were nothing if not incredibly literal. When ancient Greeks first laid eyes on a massive, aggressive, semi-aquatic mammal wallowing in the mud, they apparently thought it resembled an oversized equestrian. They smashed together the words 'hippos' (horse) and 'potamos' (river) to create a name that has stuck for millennia, despite the animal being much closer related to whales than horses.