Benzidine

noun

1. A carcinogenic yellowish, white, or reddish-gray crystalline powder, C12H12 N2, that is a derivative of biphenyl, is used in dyes, and is used to detect blood stains and cyanide.
2. The common name for para-diaminodiphenyl, one of the aromatic bases having the formula NH2.C6H4–C6H4.NH2. It is an important raw material in the preparation of many of the direct cotton colors.
3. The aromatic diamine 4,4'-diaminobiphenyl that is used in testing for cyanide, and for traces of blood