\ ˈsləj How to pronounce sludge (audio) \

Definition of sludge

1 : mud, mire especially : a muddy deposit (as on a riverbed) : ooze
2 : a muddy or slushy mass, deposit, or sediment: such as
a : precipitated solid matter produced by water and sewage treatment processes
b : muddy sediment in a steam boiler
c : a precipitate or settling (such as a mixture of impurities and acid) from a mineral oil

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Other Words from sludge

sludgy \ ˈslə-​jē How to pronounce sludgy (audio) \ adjective

Synonyms for sludge


guck (or gook), mire, muck, mud, ooze, slime, slop, slush

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Examples of sludge in a Sentence

after a day of heavy rain, the fairgrounds had turned into pure sludge I can't bring myself to read that sludge.

Recent Examples on the Web

Dorm mold became a nationwide sensation s little more than three weeks ago after a Facebook page, amn/nco/snco, posted photos of black and green sludge in Lackland living areas for technical training students. Sig Christenson,, "Almost one-third of dorm rooms at Joint Base San Antonio had mold, mildew," 17 Aug. 2019 Treated sludge from West Virginia coal mines contain heavy rare-earths in particular, which are valuable and have few suppliers outside of China. Megan Geuss, Ars Technica, "China’s saber-rattling on rare-earths trade has US officials looking for options," 30 May 2019 While the bottles did not smell, chemical analysis of the sludge did reveal some of the ingredients. Jason Daley, Smithsonian, "Cleopatra May Have Once Smelled Like This Recreated Perfume," 9 Aug. 2019 The mine discharged six tons of toxic sludge daily before an EPA cleanup. Matthew Brown, The Seattle Times, "50M gallons of polluted water pours daily from US mine sites," 20 Feb. 2019 Crops and animals have died around a crusty lake of radioactive black sludge formed from mining waste near a major mining site in Baotou, Inner Mongolia. Los Angeles Times, "The hidden costs of China’s rare-earth trade," 29 July 2019 Much of the sludge is stored in single-wall underground tanks that have leaked. Ralph Vartabedian,, "Nuclear waste will be classified as safer under a controversial Trump administration change," 5 June 2019 On August 12, 1960, Barbara was sedated, and her hips and legs were punctured fifty times with a large-bore needle to extract the crimson sludge of her bone marrow. Siddhartha Mukherjee, The New Yorker, "The Promise and Price of Cellular Therapies," 15 July 2019 The sickening sludge isn’t just concentrated in the Gulf of Mexico., "‘All bets are off’: Toxic algae bloom shutters Mississippi beaches, causes worry in Alabama," 12 July 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'sludge.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of sludge

15th century, in the meaning defined at sense 1

History and Etymology for sludge

Middle English slugge, perhaps alteration of slicche mud, slush; akin to Old High German slīh mire

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Dictionary Entries near sludge


slub yarn



sludge acid



Statistics for sludge

Last Updated

2 Sep 2019

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Time Traveler for sludge

The first known use of sludge was in the 15th century

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More Definitions for sludge



English Language Learners Definition of sludge

: thick, soft, wet mud
: a soft, thick material that is produced in various industrial processes (such as in the treatment of sewage)
: a thick material that can form in the oil in an engine and cause engine problems


\ ˈsləj How to pronounce sludge (audio) \

Kids Definition of sludge

: a soft muddy mass resulting from sewage treatment


\ ˈsləj How to pronounce sludge (audio) \

Medical Definition of sludge

 (Entry 1 of 2)

: a semisolid precipitated mass or deposit biliary sludge especially : sludged blood
sludged; sludging

Medical Definition of sludge (Entry 2 of 2)

: to form sludge positions that cause blood to sludge— L. K. Altman

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More from Merriam-Webster on sludge

Rhyming Dictionary: Words that rhyme with sludge

Thesaurus: All synonyms and antonyms for sludge

Spanish Central: Translation of sludge

Nglish: Translation of sludge for Spanish Speakers

Britannica English: Translation of sludge for Arabic Speakers

Comments on sludge

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authorized for issue (as a bond)

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