sludge

noun

ˈsləj 

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

3

: slush sense 5

sludgy

ˈslə-jē 

adjective

Synonyms of sludge

• mud

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

Tanks full of radioactive sludge exposed him to at least 48 potentially hazardous chemicals. — Lizz Giordano, ProPublica, 22 Oct. 2026

Investigators have also removed drums containing an oily, sludge-like material from the property and have investigated the home for signs of wet cremation, when a mix of chemicals are used to break down human remains. — Joe Holden, CBS News, 21 Oct. 2026

And at some point, you’re just locked in some attic getting a sludge transfusion from your apparently satanist mother in law? — Mikey O'Connell, HollywoodReporter, 17 Oct. 2026

Just a noxious river of sludge and foul wind enveloping everything in the vicinity. — Josh Brown,sean Russo, CNBC, 8 Oct. 2026

Word History

Etymology

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

First Known Use

15th century, in the meaning defined at sense 1

Rhymes for sludge

• budge
• drudge
• frage
• fudge
• grudge
• judge
• mudge
• nudge
• rudge
• smudge
• trudge
• adjudge

Kids Definition

sludge

noun

ˈsləj 

1

: mud, mire

2

: a muddy or slushy mass

especially : solid matter produced by water and sewage treatment processes

sludgy

ˈsləj-ē 

adjective

Medical Definition

sludge

1 of 2 noun

ˈsləj 

: a semisolid precipitated mass or deposit

biliary sludge

especially : sludged blood

sludge

2 of 2 intransitive verb

sludged; sludging

: to form sludge

positions that cause blood to sludge

—L. K. Altman