- a grayish, crystalline, slightly water-soluble, basic compound, C12H12N2, usually derived from nitrobenzene: used chiefly in the synthesis of certain azo dyes, especially Congo red.
- a grey or reddish poisonous crystalline powder that is used mainly in the manufacture of dyes, esp Congo red. Formula: NH 2 (C 6 H 4) 2 NH 2
