brightness

noun

1. the quality of being bright.
2. Optics. the luminance of a body, apart from its hue or saturation, that an observer uses to determine the comparative luminance of another body. Pure white has the maximum brightness, and pure black the minimum brightness.

noun

1. the condition of being bright
2. physics a former name for luminosity (def. 4)
3. psychol the experienced intensity of light