luminance

[loo-muh-nuh ns] /ˈlu mə nəns/
noun
1.
the state or quality of being luminous.
2.
Also called luminosity. the quality or condition of radiating or reflecting light:
the blinding luminance of the sun.
3.
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
1875-80; < Latin lūmin- (stem of lūmen) light + -ance
Examples from the web for luminance
  • The flashlight highlighted the anemone's dazzling luminance, while the setting sun added a sense of atmosphere.
British Dictionary definitions for luminance

luminance

/ˈluːmɪnəns/
noun
1.
a state or quality of radiating or reflecting light
2.
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
Word Origin and History for luminance
n.

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

luminance in Science
luminance
  (l'mə-nəns)   
The luminous intensity of a light source per unit area. Occasionally the lambert unit is used to measure luminance. Also called photometric brightness.
luminance in Technology