[ loo-muh n ]
/ ˈlu mən /

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.

Nearby words

  1. lumbricide,
  2. lumbricoid,
  3. lumbricosis,
  4. lumbricus,
  5. lumbus,
  6. lumen-hour,
  7. lumholtz's kangaroo,
  8. lumiere,
  9. luminaire,
  10. luminal

Origin of lumen

1870–75; < New Latin, special uses of Latin lūmen (stem lūmin-) light, window Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for lumina

British Dictionary definitions for lumina


/ (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 Formslumenal 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

Word Origin and History for lumina



unit of luminosity, 1897, coined 1894 by French physicist André-Eugène Blondel (1863-1938) from Latin lumen "light," related to lucere "to shine" (see light (n.)).

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for lumina


[ 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.
Related formslumen•al null adj.

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

Science definitions for lumina


[ 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.