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)

soots, present (3rd person singular) sooted, past participle, past sooting present participle

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

Derived Forms

• sootless
  adjective
• sootlike
  adjective

Inflected Forms

Participles

• sooting
  present
• sooted
  past

Conjugated Forms

Present

• soot
  simple
• soots
  simple
• have sooted
  perfect
• has sooted
  perfect
• am sooting
  progressive
• are sooting
  progressive
• is sooting
  progressive
• have been sooting
  perfect progressive
• has been sooting
  perfect progressive

Past

• sooted
  simple
• had sooted
  perfect
• was sooting
  progressive
• were sooting
  progressive
• had been sooting
  perfect progressive

Future

• will soot
  simple
• will have sooted
  perfect
• will be sooting
  progressive
• will have been sooting
  perfect progressive

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

Network Rail has called the Victorian tunnel one of the most hostile environments on the UK rail network, where moisture, dripping saltwater and diesel soot accelerate wear on equipment.

From BBC • May 22, 2026

“Californians face the most significant smog and soot challenges in the nation, but our air agencies have followed the science to build policies and programs to make real headway,” Barrett said.

From Los Angeles Times • May 14, 2026

Residents have posted videos on social media showing soot blanketing the city and complaining about the effects on the environment and their lives.

From The Wall Street Journal • Apr. 28, 2026

On Earth, dusty plasma can form during wildfires when soot mixes with smoke.

From Science Daily • Apr. 23, 2026

The stovepipe came clattering down from the ceiling, belching a bushel of black soot all over us and the room, including the head of Abraham Lincoln.

From "The Teacher’s Funeral" by Richard Peck

Related Words

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