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

Every bucket, every rebound, every screen oozed difficulty, as if each player was covered in sludge. —Chris Branch, New York Times, 4 June 2026

The backlash was so extensive, Gutierrez ended up backtracking on the lucrative gig entirely, in one of the clearest signs yet that AI has become toxic sludge to much of the audience Amazon is trying to woo. —Victor Tangermann, Futurism, 3 June 2026

Ironically, the onslaught of AI sludge reshaping the look and feel of life online today has been steadily compelling some viewers to embrace exploring last century’s cinema in the real world. —Alison Foreman, IndieWire, 31 May 2026

Brine is a super-concentrated, suffocating saltwater sludge, which kills marine life. —Mrigakshi Dixit, Interesting Engineering, 27 May 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