Ashes and black powdery dirt left in the fireplace after you've had a wood-burning fire is an example of soot.
Origin of sootMiddle English from Old English sot, akin to Middle Dutch soet from Indo-European base an unverified form sed-, to sit: basic sense “what settles”
Origin of sootMiddle English from Old English sōt ; see sed- in Indo-European roots.
(third-person singular simple present soots, present participle sooting, simple past and past participle sooted)
Old English sÅt, from Proto-Germanic *sÅtÄ… (“soot"), a derivation of *sitjanÄ… (whence also English sit). Cognate with Old Norse sÃ³t, Old Dutch soet and Middle Low German sÅt. Compare similar Å-grade formation from the Proto-Indo-European *sed- (“sit") in Old Irish suide (“soot") and Balto-Slavic: Lithuanian sÃºodÅ¾iai (“soot"), and Proto-Slavic *sadja (“soot") (Russian ÑÐ°ÌÐ¶Ð° (sÃ¡Å¾a), Polish and Slovak sadza, Bulgarian ÑÐ°ÌÐ¶Ð´Ð° (sÃ¡Å¾da)).