[ loo-muhn ]
/ ˈlu mən /
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noun, plural lu·mens, lu·mi·na [loo-muh-nuh]. /ˈlu mə nə/.
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. Abbreviation: lm
Anatomy. the canal, duct, or cavity of a tubular organ.
Botany. (of a cell) the cavity that the cell walls enclose.
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Origin of lumen

1870–75; <New Latin, special uses of Latin lūmen (stem lūmin-) light, window
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

How to use lumen in a sentence

British Dictionary definitions for lumen

/ (ˈluːmɪn) /

noun plural -mens or -mina (-mɪnə)
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 candelaSymbol: lm
anatomy a passage, duct, or cavity in a tubular organ
a cavity within a plant cell enclosed by the cell walls

Derived forms of lumen

lumenal or luminal, adjective

Word Origin for lumen

C19: New Latin, from Latin: light, aperture
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for lumen

[ lōōmən ]

n. pl. lumens
The inner open space or cavity of a tubular organ, as of a blood vessel.
The unit of luminous flux in the International System of Units, equal to the amount of light given out through a solid angle by a source of one candela intensity radiating equally in all directions.

Other words from lumen

lumen•al null adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for lumen

[ lōōmən ]

Plural lumens lumina
The central space within a tube-shaped body part or organ, such as a blood vessel or the intestine.
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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.