lumen

noun

lu·​men ˈlü-mən How to pronounce lumen (audio)
plural lumens also lumina ˈlü-mə-nə How to pronounce lumen (audio)
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
luminal adjective
or less commonly lumenal

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.

Example Sentences

Recent Examples on the Web Like its predecessors in the Coravin lineup, the Timeless Eleven utilizes a dual lumen needle that allows argon (an inert gas that protects the wine from oxidation) to flow into the bottle while wine flows out through the spout. Mike Desimone And Jeff Jenssen, Robb Report, 22 Nov. 2022 These energy-efficient bulbs from Xtricity are compact in size, have a good lumen output, offer a long life, and are easy to fit. Kat De Naoum, Better Homes & Gardens, 25 Oct. 2022 Its lumen output ranges from 20 to 200, and there are four levels of brightness (20 lumens for level 1, 60 lumens for level 2, 125 lumens for level 3, and 200 lumens for level 4). Toby Grey, BGR, 15 Sep. 2022 Whereas a lumen rating between 6,000 to 10,000 lumens lights up your entire yard, stairway or pathway lights can go as low as 100 to 200 lumens and still provide optimal illumination. Kaz Weida, Popular Mechanics, 29 Aug. 2022 This model also includes a 800 lumen LED bulb that should last between 15 and 20 years. Alex Rennie, Popular Mechanics, 9 Aug. 2022 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 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.

Word History

Etymology

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

First Known Use

1873, in the meaning defined at sense 1

Time Traveler
The first known use of lumen was in 1873

Dictionary Entries Near lumen

Cite this Entry

“Lumen.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/lumen. Accessed 5 Dec. 2022.

Kids Definition

lumen

noun

lu·​men ˈlü-mən How to pronounce lumen (audio)
plural lumens also lumina -mə-nə How to pronounce lumen (audio)
: a unit of light quantity equal to the light on a unit surface all points of which are at a unit distance from a point source of light having a strength of one candle

Medical Definition

lumen

noun

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

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