(Homonym: die) Substance that, applied in solution to fabrics, imparts a color resistant to washing. Direct dyes combine with the material of the fabric, yielding a colored compound; indirect dyes require the presence of another substance (a mordant), with which the fabric must first be treated; vat dyes are colorless soluble substances that on exposure to air yield an insoluble colored compound.
Naturally occurring dyes include indigo, madder (alizarin), logwood, and cochineal, but industrial dyes (introduced in the 19th century) are usually synthetic: acid green was developed 1835 and bright purple 1856.
Industrial dyes include azo dyestuffs, acridine, anthracene, and aniline.
A usually soluble substance for staining or coloring e.g. fabrics or hair; SYN. dyestuff.

To color with dye.