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

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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 The endothelial cells that make up these tiny blood vessels form a regulated barrier between the blood on one side (the lumen side of the blood vessels) and the chemical environment the brain and spinal cord float in on the other side. Gabriel A. Silva, Forbes, 6 June 2021 The Coleman 600 lumen LED lantern is a great accessory for your camping trips and a top camping gift. Outdoor Life, 26 Feb. 2021 Despite its smaller design, the 360-degree speaker delivers crisp, clear sound, while the 100 ANSI-lumen image brings excellent detail to every screen. Maya Gandara, Southern Living, 23 Mar. 2021 Typically, the higher the lumen count—which for headlamps can range from the low hundreds into the thousands—the brighter the light. Outdoor Life, 10 Mar. 2021 Turbo 1,000 lumen mode can potentially startle intruders. Lauren Corona, chicagotribune.com, 26 Sep. 2020 The low-beams are also incredibly bright, turning reflective signs into dazzling beacons, which then reflected on the wet tarmac, a reminder that those signs were designed for a more lumen-deficient era. Jonathon Ramsey, Car and Driver, 14 Dec. 2020 The trouble with looking at the lumen measurement is that it can be exaggerated by some manufacturers. Lauren Corona, chicagotribune.com, 2 Oct. 2020 In general, any bleeding in your gastrointestinal tract happens because blood vessels are exposed and bleeding into the lumen of the G.I. tract. Korin Miller, SELF, 29 Sep. 2020

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.

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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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Last Updated

12 Jun 2021

Cite this Entry

“Lumen.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/lumen. Accessed 12 Jun. 2021.

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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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