WordNet sense 1 (a carbonaceous material obtained by heating wood or other organic matter in the absence of air):

wood coal

WordNet sense 2 (a very dark grey color):

charcoal gray, charcoal grey, oxford gray, oxford grey

WordNet sense 3 (a stick of black carbon material used for drawing):

fusain

WordNet sense 4 (of a very dark grey):

charcoal-gray, charcoal-grey

WordNet sense 5 (having no hue):

achromatic