- any of a group of salts of the general formula ArN2X, in which Ar represents an aryl group and X an anion, as benzenediazonium chloride, C6H5N(N)Cl, many of which are important intermediates in the manufacture of azo dyes.
- any of a class of compounds with the general formula ArN:N – M +, where Ar is an aryl group and M is a metal atom; made by the action of nitrous acid on aromatic amines and used in dyeing
