The term 'covered in soot' can be described by two crossword solutions: GRIMY (5 letters) and ASHY (4 letters). GRIMY is an adjective that means dirty or GRIMY, usually due to a layer of soot or dust. ASHY is an adjective that describes something that is covered in ash, which is a fine powdery substance made up of tiny particles of matter that are left after something has been burned. Both words describe something that is covered in soot, which is a black or grey powdery substance made up of tiny particles of carbon that is produced when something is burned.