Soot/sʊt/ Definition 1 of 2Pro Tip 1/3Cleaning Context Soot often implies a need for cleaning, as it accumulates on surfaces. After the campfire, our pots were covered with soot. Pro Tip 2/3Visual Description Soot is visually striking, being a deep black color that stains. Her hands were stained with soot after fixing the furnace. Pro Tip 3/3Combustion Result Soot is specifically the result of incomplete combustion, often from wood or coal. The old steam engine left a trail of soot behind it.