[loo-muh-nuh ns]


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 Unabridged Dictionary, © Random House, Inc. 2019

Related Words for luminance

light, glow, brightness, fluorescence

Examples from the Web for luminance

Historical Examples of luminance

  • 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 directionSymbol: L

Word Origin for luminance

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

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

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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.