(make or become black; "The smoke blackened the ceiling"; "The ceiling blackened")
(burn slightly and superficially so as to affect color; "The cook blackened the chicken breast"; "The fire charred the ceiling above the mantelpiece"; "the flames scorched the ceiling")
(darkened by smoke; "blackened rafters")
((of the face) made black especially as with suffused blood; "a face black with fury")