Definition of "hippopotamus" []

• A large, chiefly aquatic African herbivorous mammal (Hippopotamus amphibius) having thick, dark, almost hairless skin, short legs with four toes, and a broad, wide-mouthed muzzle. Also called river horse. (noun)
• The pygmy hippopotamus. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Q: What do you call a hippopotamus who rides a train?"
• "Kirsten Anderson says that this baby pygmy hippopotamus is "ridiculously cute.""
• "What we call a hippopotamus — “river horse” — the Germans call “Flusspferd,” which literally means “river horse.”"