1. Art.a color, as red, yellow, or blue, that in mixture yields other colors. Cf. complementary color (def. 1), secondary color, tertiary color.
2. Optics.any of a set of monochromatic colors, as red, green, and blue, that are added to match or specify the chromaticity of a stimulus or sample.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.