soot

American  

[soot, soot] / sʊt, sut /

noun

1. a black, carbonaceous substance produced during incomplete combustion of coal, wood, oil, etc., rising in fine particles and adhering to the sides of the chimney or pipe conveying the smoke: also conveyed in the atmosphere to other locations.

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verb (used with object)

1. to mark, cover, or treat with soot.

soot British  

/ sʊt /

noun

1. finely divided carbon deposited from flames during the incomplete combustion of organic substances such as coal

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verb

1. (tr) to cover with soot

soot Scientific  

/ st /

1. A black, powdery substance that consists mainly of carbon and is formed through the incomplete combustion of wood, coal, diesel oil, or other materials. Because it absorbs energy from sunlight rather than reflecting it, soot is believed to be a cause of global warming, especially when it settles on snow and ice, reducing their reflectivity. Soot particles in the air are a contributing factor in respiratory diseases.

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Other Word Forms

• sootless
  adjective
• sootlike
  adjective

Etymology

Origin of soot

before 900; Middle English; Old English sōt; cognate with Old Norse sōt

Explanation

The powdery black stuff that's sometimes created when fuel burns is called soot. A chimney sweep's job is to clean all the soot and ash from inside a chimney. Soot is mostly made of carbon, and it forms when matter burns incompletely. Engines, burning coal, and house fires are all sources of soot, and soot is a major contributor to air pollution around the world. It's dangerous for people to breathe too much soot into their lungs. Soot comes from a Germanic root that literally means "what settles."

Example Sentences

The 1882 installation of the first central power station on New York’s Pearl Street signaled the end of the gas-lamp era, which had plagued cities with soot and fire hazards.

From The Wall Street Journal • Apr. 24, 2026

It used to be that coal’s biggest opponents were environmentalists who raised alarms about the soot they spew.

From Barron's • Apr. 20, 2026

Footage of the aftermath shows the entire side of the building blackened with soot with a plume of smoke rising into the air.

From BBC • Mar. 27, 2026

At the same time, more complete burning of the fuel decreases soot and particulate emissions.

From Science Daily • Mar. 13, 2026

Sketched upon the pall of soot downstream the outline of a burnt city like a black paper scrim.

From "The Road" by Cormac McCarthy

Related Words

• ash
• grit
• gunk
• residue
• sediment
• smoke