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

• guck
• gook
• mire
• muck
• mud
• ooze
• slime
• slop
• slush

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

No area of any economy may have more sludge than tariff classification. —Steve Banker, Forbes.com, 11 Apr. 2025

There’s no scientific evidence these products are effective in dissolving sludge or keeping these tiny pests away, says Oi. —Arricca Elin Sansone, Southern Living, 7 Apr. 2025

The toxic sludge is often used as farm fertilizer, thus contaminating both the food chain and public drinking water. —Carson Swick, Baltimore Sun, 24 Mar. 2025

Instead of simply breaking down the sludge, the system turns it into something useful. —Paul Smaglik, Discover Magazine, 20 Mar. 2025

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