Definition of: brightness

(brīt′nis) noun
1. The state, quality, or condition of being bright, in any sense.
2. The luminous intensity of any surface in a given direction, per unit of projected area of the surface as viewed in that direction.
3. That attribute of a color which identifies it as equivalent to some member of the achromatic color series, ranging from black or very dim, to white or very bright. Compare LIGHTNESS, HUE, SATURATION. See COLOR.