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 of brightness

• brilliancy
• brilliance
• lightness
• illumination
• luminosity

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

Such lights can adjust their brightness based on movements by pedestrians or traffic or even on weather conditions. —Ashley MacKin Solomon, San Diego Union-Tribune, 7 Nov. 2025

That is because their brightness may be strongly affected by the age of the progenitor stars of these explosive events. —Robert Lea, Space.com, 6 Nov. 2025

For stargazers in the northern hemisphere, comet 3I/ATLAS will appear in the coming week in increating brightness, moving northward in the night sky. —Hannah Millington, MSNBC Newsweek, 5 Nov. 2025

So much love is poured into each recipe to bring the brightness and warmth of the garden to your home in every season. —Meredith Kile, PEOPLE, 5 Nov. 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