'soot-covered' is a Modern English compound formed from the noun 'soot' and the past participle 'covered' of the verb 'cover'. 'soot' originates from Old English, specifically the word 'sōt', where it meant 'soot' (black residue from burning). 'cover' originates from Old French, specifically the word 'covrir', ultimately from Latin 'cooperire' where 'co-' meant 'together' and 'operire' meant 'to cover'.

'soot' changed from Old English 'sōt' (and cognates in other Germanic languages) into the modern English 'soot'. 'cover' passed into English from Old French 'covrir' (from Latin 'cooperire') and became the modern English verb 'cover' and its past participle 'covered', which forms the adjective in the compound.

Initially, the components meant 'black residue from burning' (soot) and 'to put over' (cover); combined, they meant 'covered in soot', and this literal meaning has remained stable into modern usage.