[ loo-muh-nos-i-tee ]
/ ˌlu məˈnɒs ɪ ti /

noun, plural lu·mi·nos·i·ties.

the quality of being intellectually brilliant, enlightened, inspired, etc.: The luminosity of his poetry is unequaled.
something luminous.
Astronomy. the brightness of a star in comparison with that of the sun: the luminosity of Sirius expressed as 23 indicates an intrinsic brightness 23 times as great as that of the sun.
Also called luminosity factor. Optics. the brightness of a light source of a certain wavelength as it appears to the eye, measured as the ratio of luminous flux to radiant flux at that wavelength.

Nearby words

  1. luminescence,
  2. luminescent,
  3. luminiferous,
  4. luminism,
  5. luminophore,
  6. luminosity class,
  7. luminous,
  8. luminous efficacy,
  9. luminous efficiency,
  10. luminous emittance

Origin of luminosity

1625–35; < Latin lūminōs(us) luminous + -ity

Related formsnon·lu·mi·nos·i·ty, nounself-lu·mi·nos·i·ty, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for luminosity

British Dictionary definitions for luminosity


/ (ˌluːmɪˈnɒsɪtɪ) /

noun plural -ties

the condition of being luminous
something that is luminous
astronomy a measure of the radiant power emitted by a star
physics the attribute of an object or colour enabling the extent to which an object emits light to be observedFormer name: brightness See also colour
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 luminosity



1630s, "quality of being luminous," from French luminosité or else a native formation from luminous + -ity. In astronomy, "intrinsic brightness of a heavenly body" (as distinguished from apparent magnitude, which diminishes with distance), attested from 1906.

Online Etymology Dictionary, © 2010 Douglas Harper