Pronunciation: (lOO'mu-nuns), [key]
1. the state or quality of being luminous.
2. Also called luminosity. the quality or condition of radiating or reflecting light: the blinding luminance of the sun.
3. Optics.the quantitative measure of brightness of a light source or an illuminated surface, equal to luminous flux per unit solid angle emitted per unit projected area of the source or surface.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.