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.

Examples of lumen in a Sentence

Recent Examples on the Web The newer camera also has brighter LEDs (that together put out 2,800 lumens vs. 2,600 lumens last generation) which are dimmable and have a 5,000K white color temperature. PCMAG, 5 Feb. 2024 The flashlight offers a maximum output of 1,000 lumens and a peak beam distance of 201 yards. Jessica MacDonald, Travel + Leisure, 27 Oct. 2023 The lights are dimmable and have a 4,000K white color temperature and a maximum output of 3,000 lumens. PCMAG, 5 Feb. 2024 The new efficiency standard announced by the Biden administration requires light bulbs to meet a minimum standard of producing 45 lumens per watt. Hiroko Tabuchi, New York Times, 1 Aug. 2023 With a max brightness of 1,200 lumens, these are powerful enough to easily light up a whole tent or the trail ahead. Alesandra Dubin, Travel + Leisure, 2 Jan. 2024 In addition to these excellent power tools, the kit comes with an LED work light that delivers 110 lumens of light output for clearer visibility when working in low light conditions. Kat De Naoum, Better Homes & Gardens, 5 Jan. 2024 Long-life LEDs offer an output of 400 lumens with the option for high, medium, or low brightness. Jessica MacDonald, Travel + Leisure, 27 Oct. 2023 The new standard of 45 lumens per watt effectively banned the most common incandescent bulbs, which produce about 15 lumens per watt. Jonathan Edwards, Washington Post, 18 Sep. 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'lumen.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

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 19 Mar. 2024.

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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