\Col"co*thar\ (k[o^]l"k[-o]*th[~e]r), n. [NL.
colcothar vitrioli, fr. Ar. qolqo[.t]ar.] (Chem.)
Polishing rouge; a reddish brown oxide of iron, used in
polishing glass, and also as a pigment; -- called also
{crocus Martis}.