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[slee-per] /ˈsli pər/
a person or thing that sleeps.
a heavy horizontal timber for distributing loads.
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.
a sleeping car.
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.
merchandise that is not quickly sold because its value is not immediately recognized.
Often, sleepers. one-piece or two-piece pajamas with feet, especially for children.
bunting3 .
a sofa, chair, or other piece of furniture that is designed to open up or unfold into a bed; convertible.
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.
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.
Slang. a spy; mole.
Slang. a juvenile delinquent sentenced to serve more than nine months.
Bowling. a pin that is hidden from view by another pin.
Chiefly British. a timber or beam laid in a railroad track, serving as a foundation or support for the rails; tie.
Origin of sleeper
Middle English word dating back to 1175-1225; See origin at sleep, -er1 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for sleeper
Contemporary Examples
Historical Examples
  • So keen the blade, so soft the touch, the sleeper did not wake!

  • The sounding thumps of his hoofs on the ground awoke the sleeper.

    Johnny Bear E. T. Seton
  • She had not withdrawn her hand, when the sleeper opened her eyes and started.

    Little Dorrit Charles Dickens
  • As Joe said this he stared down at the sleeper, a curious tensity in his eyes.

    The Harbor Ernest Poole
  • While he was thus engaged, the sleeper, without any starting or turning round, awoke.

    Barnaby Rudge Charles Dickens
British Dictionary definitions for sleeper


a person, animal, or thing that sleeps
a railway sleeping car or compartment
(Brit) one of the blocks supporting the rails on a railway track US and Canadian equivalent tie
a heavy timber beam, esp one that is laid horizontally on the ground
(mainly Brit) a small plain gold circle worn in a pierced ear lobe to prevent the hole from closing up
a wrestling hold in which a wrestler presses the sides of his opponent's neck, causing him to pass out
(US) an unbranded calf
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
(informal) a person or thing that achieves unexpected success after an initial period of obscurity
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
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Word Origin and History for sleeper

Old English slæpere "one who sleeps, one who is inclined to sleep much," agent noun from sleep (v.). Meaning "strong horizontal beam" is from c.1600. Meaning "dormant or inoperative thing" is from 1620s. Meaning "railroad sleeping car" is from 1875. Sense of "something whose importance proves to be greater than expected" first attested 1892, originally in American English sports jargon, probably from earlier (1856) gambling slang sense of "unexpected winning card." Meaning "spy, enemy agent, terrorist etc. who remains undercover for a long time before attempting his purpose" first attested 1955, originally in reference to communist agents in the West.

Online Etymology Dictionary, © 2010 Douglas Harper
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Slang definitions & phrases for sleeper



: a sleeper play


  1. Anything, esp a low-budget movie, a show, or a book, which achieves or probably will achieve success after a time of obscurity; dark horse: My Name is Julia Ross is the first ''sleeper'' to come to Philadelphia in months/ whose Return of the Secaucus Seven ranked among the more astute sleepers of 1980 (1892+)
  2. A player who unexpectedly and cunningly gets the ball and runs (1953+ Football)
  3. A sleeping pill or a sedative (1960s+ Narcotics)

[the first noun sense may be fr gambling term sleeper, found by 1856 and meaning both ''an unexpected winning card'' and ''a pot whose owner has ignored it, and hence is free to anyone who takes it'']

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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