noun
: any of a very large class of dyes characterized by the presence of one or more azo groups, made by coupling an aromatic diazonium compound with a coupling component (as a phenol, an aromatic amine, or a pyrazolone), and noted for their versatility, being applied by various processes in dyeing or coloring a wide range of materials (as textile fibers, leather, plastics, foods, drugs, and cosmetics) and being used in making pigments and diazotypes — see dye table I