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

Brine is a super-concentrated, suffocating saltwater sludge, which kills marine life. —Mrigakshi Dixit, Interesting Engineering, 27 May 2026

With just enough personality to distinguish itself from the endless churn of streaming sludge only claiming to deliver the same caliber of laughs online, Appel’s latest film tones down the surrealism at work in his earlier, far more outrageous Weird Al biopic from 2022. —Alison Foreman, IndieWire, 27 May 2026

The line included eco-friendly finished metal buttons in neutral tones carrying a LCA certification, indicating reduced CO2 emissions, chemical consumption, sludge generation, water usage and electricity consumption. —Andrea Onate, Footwear News, 26 May 2026

Mitch drilled a hole into his home’s concrete foundation in hopes of diverting the sludge out of the house and into the yard. —Nick Bowlin, ProPublica, 18 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