What is the Spanish word for "donkey"?

The story behind the answer

Burro is the Spanish word for “donkey.” You might also see asno as a more formal term. The other options name different animals: perro (dog), toro (bull), and caballo (horse).

Fun context: Burro likely comes from the Latin burricus (“small horse”), and Spanish also has the variant borrico. A handy memory trick is the popular food word burrito, which literally means “little donkey”—the rolled tortilla was said to resemble the bundles a donkey might carry. Remember: burro = donkey; mula is “mule,” and caballo is “horse.”