lumen

lu·men  (lmn)

n. pl. lu·mens or lu·mi·na (-m-n)

1. Anatomy The inner open space or cavity of a tubular organ, as of a blood vessel or an intestine.

2. Abbr. lm Physics The unit of luminous flux in the International System, equal to the amount of light given out through a solid angle by a source of one candela intensity radiating equally in all directions. See Table at measurement.

3. Botany The cavity bounded by a plant cell wall.

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[Latin lmen, an opening, light; see leuk- in Indo-European roots.]

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lumen·al, lumin·al adj.

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lumen  (lmn)

Plural lumens or lumina

1. The central space within a tube-shaped body part or organ, such as a blood vessel or the intestine.

2. The SI derived unit used to measure the amount of light passing through a given area per second. One lumen is equal to the luminous flux passing per unit solid angle from a light source with a strength of one candela.

Thesaurus

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 lm luminous flux unit - a measure of luminous flux per unit area
	2.	lumen - a cavity or passage in a tubular organ; "the lumen of the intestine" bodily cavity, cavum, cavity - (anatomy) a natural hollow or sinus within the body