sleeper

American  

[slee-per] / ˈsli pər /

noun

sleepers plural

1. a person or thing that sleeps.

2. a heavy horizontal timber for distributing loads.

3. Building Trades.

   1. any long wooden, metal, or stone piece lying horizontally as a sill or footing.

   2. any of a number of wooden pieces, laid upon the ground or upon masonry or concrete, to which floorboards are nailed.

4. a sleeping car.

5. Informal. something or someone that becomes unexpectedly successful or important after a period of being unnoticed, ignored, or considered unpromising or a failure.

   The play was the sleeper of the season.

6. merchandise that is not quickly sold because its value is not immediately recognized.

7. Often sleepers. one-piece or two-piece pajamas with feet, especially for children.

8. bunting.

9. a sofa, chair, or other piece of furniture that is designed to open up or unfold into a bed; convertible.

10. Also called sleep, sand.  a globule that forms at the inner corner of the eye, especially during sleep, from the accumulated secretion of the glands of the eyelid.

11. any of several gobioid fishes of the family Eleotridae, of tropical seas, most species of which have the habit of resting quietly on the bottom.

12. Slang. a spy; mole.

13. Slang. a juvenile delinquent sentenced to serve more than nine months.

14. Bowling. a pin that is hidden from view by another pin.

15. Chiefly British. a timber or beam laid in a railroad track, serving as a foundation or support for the rails; tie.

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sleeper British  

/ ˈsliːpə /

noun

1. a person, animal, or thing that sleeps

2. a railway sleeping car or compartment

3. US and Canadian equivalent: tie.  one of the blocks supporting the rails on a railway track

4. a heavy timber beam, esp one that is laid horizontally on the ground

5. a small plain gold circle worn in a pierced ear lobe to prevent the hole from closing up

6. a wrestling hold in which a wrestler presses the sides of his opponent's neck, causing him to pass out

7. an unbranded calf

8. Also called: sleeper goby.  any gobioid fish of the family Eleotridae, of brackish or fresh tropical waters, resembling the gobies but lacking a ventral sucker

9. informal a person or thing that achieves unexpected success after an initial period of obscurity

10. a spy planted in advance for future use, but not currently active

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Other Word Forms

Noun Inflected Forms

• sleepers
  plural

Etymology

Origin of sleeper

Middle English word dating back to 1175–1225; see origin at sleep, -er ¹

Explanation

A sleeper is something that succeeds when no one thought it would. That low-tech movie about shark attacks that you shot on vacation and edited in your basement? It could be a sleeper if you market it in the right way. You probably know that sleeper can be used in an obvious sense to refer to someone who is asleep. But you also may hear the word used to describe something that becomes an unexpected success, like "a sleeper of a film" featuring unknown actors that ends up becoming the big summer hit. This sense of the word may have originated in the world of gambling in the nineteenth century. When a card player unexpectedly drew a winning card, the card was called "a sleeper."

Example Sentences

See Examples For:

sleeper sleepers

Some people were crazy about how he had a beard and said that he was in a sleeper cell and all this stuff.

From Salon ● Jul. 20, 2026

"All it means is that I get home later in the evening, meaning early in the morning. And I'm not a big sleeper anyway."

From Barron's ● Jun. 16, 2026

As for a sleeper game, if I squint hard enough, I can see a world where Scotland vs.

From The Wall Street Journal ● Jun. 12, 2026

Good work, however, won’t be denied, even if Broadway producers have perhaps overlearned the lesson of last year’s sleeper, Cole Escola’s “Oh, Mary!”

From Los Angeles Times ● Jun. 8, 2026

People particularly enjoyed taking in the Pullman porters, the Black men whom industrialist George Pullman hired to serve the sleeper cars on his trains.

From "Reaching for the Moon" by Katherine Johnson

Burnham referenced the Everyone In scheme during the Covid-19 pandemic, when thousands of rough sleepers across England were helped with housing.

From BBC ● Jul. 20, 2026

That compares to 473 rough sleepers in 2024 and 290 in 2023.

From BBC ● May 4, 2026

Product designers are coming up with novel ways to rouse deep sleepers that border on diabolical, including clocks that deliver 300-volt electric shocks and donate snoozers’ money to charity.

From The Wall Street Journal ● Mar. 6, 2026

Probably that’s what woke the residential sleepers, who got up next.

From Slate ● Jan. 27, 2026

The abrupt halt had wakened a few sleepers.

From "Night" by Elie Wiesel

Related Words

• agent
• detective
• informer
• investigator
• mole
• operative
• secret agent
• secret service
• undercover agent