boneblack

American  

[bohn-blak] / ˈboʊnˌblæk /

Or bone black

noun

1. a black, carbonaceous substance obtained by calcining bones in closed vessels, used as a black pigment, a decolorizing agent, etc.

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boneblack British  

/ ˈbəʊnˌblæk /

noun

1. a black residue from the destructive distillation of bones, containing about 10 per cent carbon and 80 per cent calcium phosphate, used as a decolorizing agent and pigment

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Etymology

Origin of boneblack

First recorded in 1805–15; bone ( def. ) + black