luminosity

noun

lu·​mi·​nos·​i·​ty ˌlü-mə-ˈnä-sə-tē 

plural luminosities

1

a

: the quality or state of being luminous

b

: something luminous

2

a

: the relative quantity of light

b

: relative brightness of something

3

: the relative quantity of radiation emitted by a celestial source (such as a star)

Synonyms

• brightness
• brilliance
• brilliancy
• candor
• dazzle
• effulgence
• illumination
• lambency
• lightness
• luminance
• luminousness
• luster
• lustre
• lustrousness
• radiance
• refulgence
• splendor

Examples of luminosity in a Sentence

the luminosity of the fireflies made for an enchanting nighttime show

Recent Examples on the Web

The array of explosions also varied in terms of luminosity, which will aid researchers in their search for answers to dark energy and the acceleration of the universe. —Jack Knudson, Discover Magazine, 14 Feb. 2025

Pink and gold pearl add luminosity, while the brand's signature blend of green tea, rice, and algae delivers hydration. —Annie Blackman, Allure, 2 Dec. 2024

That’s because some four billion years ago, our sun had only about 70 percent of its current luminosity. —Bruce Dorminey, Forbes, 20 Oct. 2024

One is directly, by observing 'standard candles' — that is, objects with predictable luminosities such as Cepheid variables, type Ia supernova explosions, and red giant stars — in galaxies and determining how far away they are based on the apparent brightness of these standard candles. —Keith Cooper, Space.com, 22 Jan. 2025

Word History

Etymology

borrowed from Middle French & Medieval Latin; Middle French luminosité, borrowed from Medieval Latin lūminōsitāt-, lūminōsitās, from Latin lūminōsus "full of light, luminous" + -itāt-, -itās -ity

First Known Use

1634, in the meaning defined at sense 1a

Kids Definition

luminosity

noun

lu·​mi·​nos·​i·​ty ˌlü-mə-ˈnäs-ət-ē 

plural luminosities

1

: the quality or state of being luminous : brightness

2

: something luminous

Medical Definition

luminosity

noun

lu·​mi·​nos·​i·​ty ˌlü-mə-ˈnäs-ət-ē 

plural luminosities

1

: the quality or state of being luminous

2

a

: the relative quantity of light

b

: the comparative degree to which light of a given wavelength induces the sensation of brightness when perceived