Dictionary.com
Thesaurus.com
Synonyms

sleeper

American  
[slee-per] / ˈsli pər /

noun

  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.


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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of sleeper

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

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

A heated mattress pad can offer many of the same benefits, often with separate zones for two sleepers, and with inconspicuous wiring.

From The Wall Street Journal

“Sinners” became a sleeper hit after its release in April, one of those increasingly rare films to combine both critical and box office success.

From The Wall Street Journal

Solicitor General Ellie Reeves said: "Vulnerable people, including rough sleepers and veterans, were promised homes, while investors who funded millions of pounds were promised returns. Both groups deserve answers."

From BBC

“This was a sleeper issue that people did not pay much attention to before the pandemic. Then things got extremely intense,” Saver said.

From Salon

He previously played a KGB sleeper agent in The Americans, for which he won an Emmy Award for his acting in 2018.

From BBC