from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Any pigment that is unstable in the presence of light; used especially of the chromophore pigments in the rod cells and cone cells of the eye
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a special pigment found in the rods and cones of the retina
Sorry, no etymologies found.