brightness

noun

bright·​ness ˈbrīt-nəs 

1

a

: the quality or state of being bright

also : an instance of such a quality or state

b

: luminance

2

: the attribute of light-source colors by which emitted light is ordered continuously from light to dark in correlation with its intensity compare hue sense 2c, lightness entry 1 sense 2a, saturation sense 4

Synonyms

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

Examples of brightness in a Sentence

the brightness of the sunshine made me squint after an afternoon spent in a darkened movie theater

Recent Examples on the Web

Nearly equal in brightness, the contrast in color will be striking. —Jamie Carter, Forbes.com, 16 June 2025

Enter the clip book light, a good way to light up the page at a brightness suitable for not-so-new eyes without harshing the reading vibes. —Ars Staff, ArsTechnica, 13 June 2025

Sparkling water or soda (for fizz) Fresh lemon or lime juice (adds brightness) Honey or agave syrup (optional for extra sweetness) Ice cubes Mint leaves (for garnish) Step-By-Step Guide Prep Your Strawberries: Muddle the fresh strawberries in a cocktail shaker or large glass. —Matt Rozo, Mercury News, 12 June 2025

Interestingly, the inner moons Ariel and Umbriel show no significant difference in brightness between their leading and trailing sides — possibly because the drifting dust doesn't reach them, thanks to shielding by Titania and Oberon. —Sharmila Kuthunur, Space.com, 11 June 2025

Word History

First Known Use

before the 12th century, in the meaning defined at sense 1a

Rhymes for brightness

• lightness
• rightness
• tightness
• whiteness
• politeness
• uprightness

Medical Definition

brightness

noun

bright·​ness ˈbrīt-nəs 

: the one of the three psychological dimensions of color perception by which visual stimuli are ordered continuously from light to dark and which is correlated with light intensity compare hue, saturation sense 4a