LUMINOSITY

luminosity, brightness, brightness level, luminance, luminousness, light

(noun) the quality of being luminous; emitting or reflecting light; “its luminosity is measured relative to that of our sun”

Source: WordNet® 3.1

Noun

luminosity (plural luminosities)

(uncountable) the state of being luminous, or a luminous object; brilliance or radiance

(physics) the ratio of luminous flux to radiant flux at the same wavelength; the luminosity factor

(astronomy) the rate at which a star radiates energy in all directions

Source: Wiktionary

Lu`mi*nos"i*ty, n.

Definition: The quality or state of being luminous; luminousness.

Source: Webster’s Unabridged Dictionary 1913 Edition