\ 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

Two multibillion-dollar industrial facilities intended to turn highly radioactive sludge into solid glass at the Hanford nuclear site have been essentially mothballed. Ralph Vartabedian,, "Nation’s most ambitious project to clean up nuclear weapons waste has stalled at Hanford," 4 June 2019 The dam’s collapse unleashed a torrent of sludge that swallowed an employee cafeteria, offices and nearby homes. Rhiannon Hoyle, WSJ, "After Brazil Tragedy, Mining Firms Call for New Oversight of Waste Dams," 25 Feb. 2019 Major shoe lovers know the struggle: winter snow—or even worse, sludge—means retiring one’s favorite footwear in favor of no-frills snow boots. Christian Allaire, Vogue, "Only Rihanna Can Pull Off This Wildly Impractical Winter Shoe," 7 Feb. 2019 Nineteen people were killed, hundreds were left homeless and hundreds of miles of river valleys were polluted by the toxic sludge. Jeffrey T. Lewis, WSJ, "Death Toll in Brazilian Mining-Dam Disaster Jumps to 34," 26 Jan. 2019 Residents have watched the river’s water turn red as it has been contaminated by the mining sludge released by Friday’s accident. Jeffrey T. Lewis, WSJ, "Brazilian Town Devastated by Dam Burst Faces Threat From Second Dam," 27 Jan. 2019 Now push a thick rag through the trap to wipe out any stuck-on sludge or debris. Joseph Truini, Popular Mechanics, "How to Unclog a Drain," 26 Jan. 2019 The containers are loaded with a material called sewer sludge or biosolids, which is the solid material left behind after conventional wastewater treatment processes. Dennis Pillion,, "New York poop train won't derail Parrish Coal Fest," 6 Apr. 2018 The water boils off and all that's left is a few teaspoonfuls of sludge. Mike Allen, Popular Mechanics, "How to Dispose of Hazardous Waste Without Damaging the Environment," 9 Oct. 2018

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

10 Jun 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

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