n. [ Gr. &unr_; color + &unr_; to show. ] (Physiol.) A general name for the several coloring matters, red, green, yellow, etc., present in the inner segments in the cones of the retina, held in solution by fats, and slowly decolorized by light; distinct from the photochemical pigments of the rods of the retina. [ 1913 Webster ]