The quality of being luminous. / The amount of light that passes through, is emitted, or is reflected from a particular area, and falls within a given solid angle.

plural of luminance

Emitting light; glowing brightly; shining. / Brightly illuminated. / Clear; enlightening; easy to understand.

In a luminous manner, brightly, glowingly.

(biology) of or pertaining to the lumen / (physics) of or pertaining to the nature of light / (physics) light-speed; having the speed of light (usually in the void)

(medicine) The drug phenobarbital.

That illuminates; luminous.

An illuminating agent.

With regard to the lumen

The quality of being luminous.