noun.
any solublepigment used for dyeing the hair, fabric etc
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
a usually soluble substance for staining or coloring e.g. fabrics or hair
Word Usage
"In a few cases the dyestuff is a zinc compound, and zinc in small traces may possibly be fixed by the material, but this metal is not known to be actively noxious."