[slou for 1, 2, 4; sloo for 3]
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  1. an area of soft, muddy ground; swamp or swamplike region.
  2. a hole full of mire, as in a road.
  3. Also slew, slue. Northern U.S. and Canadian. a marshy or reedy pool, pond, inlet, backwater, or the like.
  4. a condition of degradation, despair, or helplessness.

Origin of slough

before 900; Middle English; Old English slōh; cognate with Middle Low German slōch, Middle High German sluoche ditch



or sluff

  1. the outer layer of the skin of a snake, which is cast off periodically.
  2. Pathology. a mass or layer of dead tissue separated from the surrounding or underlying tissue.
  3. anything that is shed or cast off.
  4. Cards. a discard.
verb (used without object)
  1. to be or become shed or cast off, as the slough of a snake.
  2. to cast off a slough.
  3. Pathology. to separate from the sound flesh, as a slough.
  4. Cards. to discard a card or cards.
verb (used with object)
  1. to dispose or get rid of; cast (often followed by off): to slough off a bad habit.
  2. to shed as or like a slough.
  3. Cards. to discard (cards).
Verb Phrases
  1. slough over, to treat as slight or trivial: to slough over a friend's mistake.

Origin of slough

1250–1300; Middle English slughe, slouh skin of a snake; cognate with German Schlauch skin, bag
Related formsslough·i·ness, nounslough·y, adjectiveun·sloughed, adjectiveun·slough·ing, adjective

Synonyms for slough

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6. molt. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for slough

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British Dictionary definitions for slough


  1. a hollow filled with mud; bog
  2. (sluː) US and Canadian
    1. (in the prairies) a large hole where water collects or the water in such a hole
    2. (in the northwest) a sluggish side channel of a river
    3. (on the Pacific coast) a marshy saltwater inlet
  3. despair or degradation
Derived Formssloughy, adjective

Word Origin for slough

Old English slōh; related to Middle High German sluoche ditch, Swedish slaga swamp


  1. any outer covering that is shed, such as the dead outer layer of the skin of a snake, the cellular debris in a wound, etc
  2. Also: sluff bridge a discarded card
  1. (often foll by off) to shed (a skin, etc) or (of a skin, etc) to be shed
  2. Also: sluff bridge to discard (a card or cards)
Derived Formssloughy, adjective

Word Origin for slough

C13: of Germanic origin; compare Middle Low German slū husk, German Schlauch hose, Norwegian slō fleshy part of a horn


  1. an industrial town in SE central England, in Slough unitary authority, Berkshire; food products, high-tech industries. Pop: 126 276 (2001)
  2. a unitary authority in SE central England, in Berkshire. Pop: 118 800 (2003 est). Area: 28 sq km (11 sq miles)
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

Word Origin and History for slough

"muddy place," Old English sloh "soft, muddy ground," of uncertain origin. Cf. Middle Low German sloch "muddy place," Middle High German sluoche "ditch." Figurative use (e.g. of moral sunkenness or Bunyan's "Slough of Despond," 1678) attested from mid-13c.


"to cast off" (as the skin of a snake or other animal), 1720, originally of diseased tissue, from Middle English noun slough "shed skin of a snake" (see slough (n.)). Related: Sloughed; sloughing.


"cast-off skin" (of a snake or other animal), early 14c., slughe, slouh, probably related to Old Saxon sluk "skin of a snake," Middle High German sluch "snakeskin, wineskin," Middle Low German slu "husk, peel, skin," German Schlauch "wineskin;" from Proto-Germanic *sluk-, of uncertain origin, perhaps from PIE root *sleug- "to glide."

Online Etymology Dictionary, © 2010 Douglas Harper

slough in Medicine


  1. A layer or mass of dead tissue separated from surrounding living tissue, as in a wound, a sore, or an inflammation.
  1. To separate from surrounding living tissue. Used of dead tissue.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

slough in Science


  1. The dead outer skin shed by a reptile or an amphibian.
  1. To shed an outer layer of skin.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.