a substance that may be naturally-occurring or artificially-made, used to change something's color or add color to something, or the color that results from such a process;
e.g. You can use dye to make your hair any color you'd like.
(verb)
to change something's color or to add color to it using a special substance, typically by dipping the thing in a solution containing the coloring agent;
e.g. He plans to dye the shirt blue to make his costume.
(verb)
to be capable of taking up color during a coloring process, or to be capable of coloring something;
e.g. Some fabrics dye very quickly while others take more repetitions to turn the desired color.