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luminosity

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

noun

plural

luminosities

  1. luminance.

  2. the quality of being intellectually brilliant, enlightened, inspired, etc..

    The luminosity of his poetry is unequaled.

  3. something luminous.

  4. 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.

  5. 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.

luminosity British  
/ ˌluːmɪˈnɒsɪtɪ /

noun

  1. the condition of being luminous

  2. something that is luminous

  3. astronomy a measure of the radiant power emitted by a star

  4. Former name: brightness.  physics the attribute of an object or colour enabling the extent to which an object emits light to be observed 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

Other Word Forms

  • nonluminosity noun
  • self-luminosity noun

Etymology

Origin of luminosity

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

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

He aptly describes the projectors’ beams of luminosity as “light sculptures.”

From Los Angeles Times • Feb. 23, 2026

“I have no medium that can give me color of such wonderful luminosity as the Autochrome plate,” wrote the photographer Edward Steichen in 1908.

From The Wall Street Journal • Nov. 21, 2025

"Their luminosity and chemical production naturally explain the nitrogen-enriched proto-galaxies that we now observe in the early universe with the JWST."

From Science Daily • Nov. 6, 2025

The Guardian's three star review said his "words glitter with feeling" and added that he "singularly shines, his luminosity putting the others slightly in the shade".

From BBC • Feb. 19, 2025

Conversely, if we knew the luminosity of stars in other galaxies, we could work out their distance by measuring their apparent brightness.

From "A Brief History of Time: And Other Essays" by Stephen Hawking

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.