Definition of soot in US English:



  • A black powdery or flaky substance consisting largely of amorphous carbon, produced by the incomplete burning of organic matter.

    • ‘Diesel particulate matter consists of soot mixed with anything from volatile organic compounds to sulphur and nitrous oxides.’
    • ‘Very low particulate, soot, and volatile organic emissions are released when it is burned.’
    • ‘Black was carbon, obtained from soot or charcoal, which had to be mixed with size to make it compatible with the fresco technique.’
    • ‘The ring had black soot on it, but one thing was clear, and that was a glistening amethyst crystal in the center.’
    • ‘The gas supply to my apartment block has been cut off, and the tap water is black with soot and dirt, but otherwise everything is normal.’
    • ‘The major pollutant in the area is particulates - tiny particles of dust or soot which get lodged in people's lungs and can damage health.’
    • ‘It is caused by tiny airborne particles of soot, ash and sulphur dioxide reflecting back the heat of the sun.’
    • ‘It is made from pollution and particles from cars, industry, and ash and soot from the burning of forests and from the wood used for cooking.’
    • ‘Their hairs are a bit singed and their faces are black from soot.’
    • ‘Because it is a lot cheaper to reduce soot emissions than to reduce carbon dioxide emissions.’
    • ‘What impact, if any, does soot and black carbon from fires have on the glaciers of Kilimanjaro?’
    • ‘We were constantly faced with black soot falling on the grass, on our houses.’
    • ‘None of these vessels was apparently used over fire, as they lack soot marks and charred organic remains.’
    • ‘The petroleum soot is not formed by solid-phase charring of fuel but is produced by recombination and coagulation of aromatic molecules in the gas phase.’
    • ‘Particulate matter, or soot, is produced by coal-fired power plants and diesel engines.’
    • ‘The residue of soot and ashes left from the fireplace is apparent on the surface.’
    • ‘If the wine smelt of soot, hot tarmac or burnt rubber, you knew it was a South African.’
    • ‘But equipment operators still face the problems of determining what is behind the layer of black char and soot on the stem.’
    • ‘Most candles contain paraffin, a petroleum-based wax that produces black soot when burned.’
    • ‘Besides diamonds, other forms of carbon found in nature include charcoal, coal, and soot.’


[with object]
  • Cover or clog (something) with soot.

    • ‘The tremendous heat has consumed all vegetation, destabilized ground areas, sooted the work environment and caused burned trees to become unsafe.’


  • (as) black as soot

    • Intensely black.

      • ‘And I never would have believed it a military unit, even one from the North, cause every face I saw was as black as soot.’
      • ‘Sato entered the now dark lab in search of Cornelius who was as black as soot.’
      • ‘The next day dawned overcast and louring, the clouds as black as soot.’
      • ‘He pulled back his hood with a hand as black as soot.’
      • ‘The skin was black as soot, and smooth as if not really skin at all.’


Old English sōt, of Germanic origin; related to German dialect Sott, from an Indo-European root shared by the verb sit.