1. In colour theory, an aspect of the perceived intensity of a colour referring to the colourfulness of a stimulus relative to the brightness of another stimulus that appears white under similar viewing conditions. Chromatic colours are all those other than black, white, and grey. See also saturation.
2. In television transmission, the part of the signal (sub-carrier) containing information on colour hue and saturation.
3. A measure of the intensity of a particular colour on a television screen in relation to a standard colour of equal luminance.