lumen

noun
lu·​men | \ ˈlü-mən How to pronounce lumen (audio) \
plural lumens also lumina\ ˈlü-​mə-​nə How to pronounce lumen (audio) \

Definition of lumen

1 : the cavity of a tubular organ or part the lumen of a blood vessel
2 : the bore of a tube (as of a hollow needle or catheter)
3 : a unit of luminous flux equal to the light emitted in a unit solid angle by a uniform point source of one candle intensity

Other Words from lumen

luminal or less commonly lumenal \ ˈlü-​mə-​nᵊl How to pronounce lumen (audio) \ adjective

Did you know?

There are two common units for measuring light, the candela and the lumen. Both are recognized as standard international units, which also include the second (for time), the kilogram (for weight), and the meter (for length). The candela is a measure of intensity; an ordinary candle gives off light with the intensity of about one candela. The lumen is a measure of "luminous flux;" a standard 100-watt lightbulb gives off 1500–1700 lumens. Luminous flux indicates how much light is actually perceived by the human eye. Technologies vary in how efficiently they turn electricity into light; halogen lights produce about 12 lumens per watt, ordinary incandescent lightbulbs produce about 15 lumens per watt, and compact fluorescent bulbs produce about 50 lumens per watt.

Examples of lumen in a Sentence

Recent Examples on the Web Inside, there are several essential survival tools, including a folding pocket knife, a paracord survival bracelet, and a high-lumen tactical flashlight, plus an 11-in-1 tool and first-aid supplies. Rachel Klein, Popular Mechanics, 2 June 2022 Front-country campers, on the other hand, can sacrifice smaller size for a larger battery and higher lumen output. Mike Richard, Men's Health, 13 May 2022 One lux is equivalent to one lumen per 10.8 square feet. Wes Siler, Outside Online, 18 Aug. 2020 For sleep, your bedroom should be as dark as possible with no more than a single lumen of yellow light shining in the space. Sonya Collins, Fortune, 27 Apr. 2022 There are a few key elements that set projectors apart, and one of the most important is brightness, measured in lumen. Gabrielle Hondorp, Popular Mechanics, 22 Apr. 2022 This is because unabsorbed carbohydrate draws water into the intestinal lumen and is eventually fermented in the colon, with loose stools and gas production as the unfortunate by-products. Patrick Wilson, Outside Online, 13 Apr. 2020 About half to three-quarters of ingested polyols get absorbed, meaning that a portion of them hang around in the gut’s lumen. Patrick Wilson, Outside Online, 7 Aug. 2020 On a mechanistic level, unabsorbed polyols draw water out of your body and into your gut lumen, resulting in loose, watery stools. Patrick Wilson, Outside Online, 7 Aug. 2020 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'lumen.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of lumen

1873, in the meaning defined at sense 1

History and Etymology for lumen

New Latin lumin-, lumen, from Latin, light, air shaft, opening

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Statistics for lumen

Last Updated

6 Jul 2022

Cite this Entry

“Lumen.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/lumen. Accessed 12 Aug. 2022.

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More Definitions for lumen

lumen

noun
lu·​men | \ ˈlü-mən How to pronounce lumen (audio) \
plural lumina\ -​mə-​nə How to pronounce lumen (audio) \ or lumens

Medical Definition of lumen

1 : the cavity of a tubular organ or part the lumen of a blood vessel
2 : the bore of a tube (as of a hollow needle or catheter)
3 : a unit of luminous flux equal to the light emitted in a steradian by a uniform point source of one candle intensity

More from Merriam-Webster on lumen

Britannica English: Translation of lumen for Arabic Speakers

Britannica.com: Encyclopedia article about lumen

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