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[loo-muh-nuh ns] /ˈlu mə nəns/
the state or quality of being luminous.
Also called luminosity. the quality or condition of radiating or reflecting light:
the blinding luminance of the sun.
Optics. the quantitative measure of brightness of a light source or an illuminated surface, equal to luminous flux per unit solid angle emitted per unit projected area of the source or surface.
Origin of luminance
1875-80; < Latin lūmin- (stem of lūmen) light + -ance Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for luminance
Historical Examples
  • A luminance seemed to come from above, from the unseen heights of the magnificent double staircase.

  • A few fluoros cast wan puddles of luminance on the plastic flooring.

    The Sensitive Man Poul William Anderson
  • The remainder of the big room receded into a grey twilight encircling the patch of luminance.

    The Lamp of Fate Margaret Pedler
British Dictionary definitions for luminance


a state or quality of radiating or reflecting light
a measure (in candelas per square metre) of the brightness of a point on a surface that is radiating or reflecting light. It is the luminous intensity in a given direction of a small element of surface area divided by the orthogonal projection of this area onto a plane at right angles to the direction L
Word Origin
C19: from Latin lūmen light
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
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Word Origin and History for luminance

"luminousness," 1862, from Latin luminantem (nominative luminans), present participle of luminare (see luminary).

Online Etymology Dictionary, © 2010 Douglas Harper
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luminance in Science
The luminous intensity of a light source per unit area. Occasionally the lambert unit is used to measure luminance. Also called photometric brightness.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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