brightness

n. luminosity; radiance; cheerfulness; intelligence, cleverness; clarity

Brightness is an attribute of visual perception in which a source appears to emit a given amount of light. In other words, brightness is the perception elicited by the luminance of a visual target. This is a subjective attribute/property of an object being observed."Brightness" was formerly used as a synonym for the photometric term luminance and (incorrectly) for the radiometric term radiance. As defined by the US Federal Glossary of Telecommunication Terms (FS-1037C), "brightness" should now be used only for non-quantitative references to physiological sensations and perceptions of light.
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Brightness said of a fleece of wool, a desirable characteristic found in superior fleeces. Consists of a white color and good light reflection. [more]Brightness - Community and Resources

Noun
1. the location of a visual perception along the black-to-white continuum
(antonym) dullness, dulness
(hypernym) light, lightness
(hyponym) glare, blaze, brilliance
2. intelligence as manifested in being quick and witty
(synonym) cleverness, smartness
(hypernym) intelligence
3. the quality of being luminous; emitting or reflecting light; "its luminosity is measured relative to that of our sun"
(synonym) luminosity, brightness level, luminance, luminousness, light
(hypernym) physical property
(hyponym) illuminance, illumination
(attribute) bright

(n.)
The quality or state of being bright; splendor; luster; brilliancy; clearness.
  

(n.)
Acuteness (of the faculties); sharpness 9wit.