mule

¹ American  

[myool] / myul /

noun

1. the sterile offspring of a female horse and a male donkey, valued as a work animal, having strong muscles, a body shaped like a horse, and donkeylike long ears, small feet, and sure-footedness.

2. any hybrid between the donkey and the horse.

3. Informal. a very stubborn person.

4. Botany. any sterile hybrid.

5. Biology. a hybrid, especially one between the canary and some other finch.

6. Slang. a person paid to carry or transport contraband, especially drugs, for a smuggler.

7. a small locomotive used for pulling rail cars, as in a coal yard or on an industrial site, or for towing, as of ships through canal locks.

8. Also called spinning mule.  a machine for spinning cotton or other fibers into yarn and winding the yarn on spindles.

9. Nautical. a large triangular staysail set between two masts and having its clew set well aft.

10. Numismatics. a hybrid coin having the obverse of one issue and the reverse of the succeeding issue, or vice versa.

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idioms

1. forty acres and a mule, a broken or unfulfilled promise, especially one with unjust, long-term consequences: an allusion to the parcels of farmland that formerly enslaved African Americans were promised and given after the Civil War and then had taken away from them.

   The protesters chanted their demand, “Real action, real justice, no forty acres and a mule.”

mule ² American  

[myool] / myul /

noun

1. a lounging slipper that covers the toes and instep or only the instep.

2. a woman's shoe resembling this.

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mule ¹ British  

/ mjuːl /

noun

1. the sterile offspring of a male donkey and a female horse, used as a beast of burden Compare hinny 1

2. any hybrid animal

   a mule canary

3. Also called: spinning mule.  a machine invented by Samuel Crompton that spins cotton into yarn and winds the yarn on spindles

4. informal an obstinate or stubborn person

5. slang a person who is paid to transport illegal drugs for a dealer

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mule ² British  

/ mjuːl /

noun

1. a backless shoe or slipper

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mule More Idioms  

1. see stubborn as a mule.

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Etymology

Origin of mule¹

First recorded before 1000; Middle English, from Old French, from Latin mūla “mule” (feminine); replacing Old English mūl, from Latin mūlus (masculine)

Origin of mule²

First recorded in 1350–1400; Middle English mule, moule “sore spot on the heel, chilblain,” perhaps from Middle Dutch mūle

Explanation

When a donkey and a horse have a baby, it's a mule. A mule, however, can not make babies — since it has an odd number of chromosomes (63, to be exact). While donkeys can be notoriously stubborn and horses can be fragile, mules are sturdy, patient, and live long lives. Mules always have a donkey father and a horse mother, while the opposite combination (a female mule and male horse) is called a hinny, and it's less common. A completely unrelated definition of mule is a slip-on shoe or slipper. This second meaning is from the Latin mulleus calceus, the footwear of Roman patricians, "red high-soled shoe."

Example Sentences

Leading a mule train into the tunnels, Ondro faces a calamity that enters the history books.

From The Wall Street Journal • Feb. 27, 2026

“The thing that we have to do before any of this is feasible at scale is to remove the mule deer,” she said.

From Los Angeles Times • Feb. 3, 2026

While the Roadster rode rough, the Straubel mule, with Mercedes’s finely tuned suspension and Tesla’s all but silent battery-powered motor, flew like a magic carpet ride.

From The Wall Street Journal • Jan. 30, 2026

Originally, she said, she was betting on a coyote, but now she’s putting her money on mule deer.

From Los Angeles Times • Jan. 26, 2026

Say a man died and left his mule to his four sons.

From "The Heart is a Lonely Hunter" by Carson McCullers

Related Words

• burro
• horse