an azo dye with more than two —N= N— azo groups; such dyes belong to the group of direct dyes.
Polyazo dyes are usually superior to other direct dyes in color fastness but are inferior in brightness. The production of polyazo dyes is more complicated than that of azo dyes and is accompanied by a series of side reactions, which results in low yields (sometimes 50 percent or less). Polyazo dyes are used for dyeing cotton and other cellulose fibers.
An example of a polyazo dye is the direct light-fast blue