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

This mechanism allows the system to automatically adjust its light sensitivity, based on the brightness of its environment. — Maryna Holovnova, New Atlas, 27 June 2026

Magnitude is the scale used by astronomers to measure the apparent brightness of an object in the night sky. — Anthony Wood, Space.com, 26 June 2026

And if the source is an object that remains steady in brightness and doesn’t flare with activity, zeroing in on the neutrino’s origin feels impossible. — Ashley Strickland, CNN Money, 26 June 2026

The big draw of this lightweight PC is its stunning 14-inch OLED screen, which delivers rich, realistic colors with DisplayHDR True Black 500 and 600 nits of peak brightness. — K. Thor Jensen, PC Magazine, 25 June 2026

Word History

First Known Use

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

Rhymes for brightness

• lightness
• rightness
• tightness
• whiteness
• finiteness
• 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