What does the name “hippopotamus” literally mean?

The name “hippopotamus” literally means “river horse.”

The word comes from Ancient Greek: hippos means “horse,” while potamos means “river.” Ancient Greek observers named the animal for its large size and its habit of spending much of the day in rivers and lakes.

Despite the name, hippopotamuses are not closely related to horses. Their closest living relatives are cetaceans, the group that includes whales and dolphins. Both groups descended from a shared ancestor that lived roughly 55 million years ago.

Hippopotamuses are semi-aquatic mammals native to sub-Saharan Africa. They can stay underwater for several minutes, although they must surface to breathe. Their barrel-shaped bodies, huge mouths, and powerful canine teeth distinguish them from true horses and other river-dwelling mammals.