LUMEN

lumen

(noun) a cavity or passage in a tubular organ; “the lumen of the intestine”

lumen, lm

(noun) 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

Source: WordNet® 3.1

Etymology

Noun

lumen (plural lumens or lumina)

(physics) In the International System of Units, the derived unit of luminous flux; the light that is emitted in a solid angle of one steradian from a source of one candela. Symbol: lm.

(anatomy) The cavity or channel within a tube or tubular organ.

(botany) The cavity bounded by a plant cell wall.

(medicine) The bore of a tube such as a hollow needle or catheter.

Source: Wiktionary

Lu"men, n.; pl. L. Lumina (#), E. Lumens (#). [L., light, an opening for light.]

1. (Photom.) (a) 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. (b) A unit of light flux, being the flux through one square meter of surface the illumination of which is uniform and of unit brightness.

2. (Biol.) An opening, space, or cavity, esp. a tubular cavity; a vacuole.

Source: Webster’s Unabridged Dictionary 1913 Edition

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