Lumen

n.	1.	(Photom.) A unit of illumination, being the amount of illumination of a unit area of spherical surface, due to a light of unit intensity placed at the center of the sphere.
	2.	(Biol.) An opening, space, or cavity, esp. a tubular cavity; a vacuole.

Noun	1.	lumen - a unit of luminous flux equal to the amount of light given out through a solid angle of 1 steradian by a point source of 1 candela intensity radiating uniformly in all directions Synonyms: lm
	2.	lumen - a cavity or passage in a tubular organ; "the lumen of the intestine"

ASA scale, British candle, Hefner candle, Scheiner scale, bougie decimale, candle, candle lumen, candle power, candle-foot, candle-hour, candle-meter, decimal candle, exposure meter, flux, foot-candle, intensity, international candle, lamp-hour, light, light meter, light quantum, lumen meter, lumen-hour, lumeter, luminous flux, luminous intensity, luminous power, lux, photon, quantum, unit of flux, unit of light