lumen

American  

[loo-muhn] / ˈlu mən /

noun

plural

lumens, lumina

1. Optics. the unit of luminous flux, equal to the luminous flux emitted in a unit solid angle by a point source of one candle intensity. lm

2. Anatomy. the canal, duct, or cavity of a tubular organ.

3. Botany. (of a cell) the cavity that the cell walls enclose.

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lumen British  

/ ˈluːmɪn /

noun

1.  lm.  the derived SI unit of luminous flux; the flux emitted in a solid angle of 1 steradian by a point source having a uniform intensity of 1 candela

2. anatomy a passage, duct, or cavity in a tubular organ

3. a cavity within a plant cell enclosed by the cell walls

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lumen Scientific  

/ lo̅o̅′mən /

plural

lumens

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.

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Other Word Forms

• lumenal adjective

Etymology

Origin of lumen

1870–75; < New Latin, special uses of Latin lūmen (stem lūmin- ) light, window

Example Sentences

While most kitchen lighting is built in, it’s possible to bring a few extra lumens to dark corners, and an extra dash of style, with plug-in lamps.

From Seattle Times

Studies have reported that when activating mutants of "Ras" proteins are expressed in mammalian epithelial cells, they are pushed toward the lumen, excreted along with other bodily waste, and eliminated by competition.

From Science Daily

Most incandescent bulbs can only create about 15 lumens with 1 watt, so they don’t meet the guidelines.

From NewsForKids.net

“If you break it down bio meaning life and lumen meaning light and so bioluminescence is really the all-encompassing term that refers to life that gives off light,” said Rouches.

From Seattle Times

The new efficiency standard announced by the Biden administration requires light bulbs to meet a minimum standard of producing 45 lumens per watt.

From New York Times