adjective. Containing a nitrogen group, especially one nitrogen atom doubly bonded to another nitrogen atom. Many common dyes contain one or a few of these groups.

adjective. azote, nitrogen

adjective. Applied loosely to compounds having nitrogen variously combined, as in cyanides, nitrates, etc.

adjective. Now especially applied to compounds containing a two atom nitrogen group (-N=N-) uniting two hydrocarbon radicals, as in azobenzene etc.

"Those include Sunset Yellow and red Ponceau 4R, the so-called azo dyes that give Irn-Bru its hyper-orange sheen."

azo-  

azo colour  azo compound  azo dye  diazo