a compound that forms coloured compounds on oxidation
2.
a substance that can be converted to a dye
3.
a bacterium that produces a pigment
chromogen in American English
(ˈkroʊmədʒən)
noun
1.
any substance that can become a pigment or coloring matter, as a substance in organic fluids that forms colored compounds when oxidized, or a compound, not itself a dye, that can become a dye