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

The pixel display on the side has configurable brightness and orientation, and displays your current charging wattage. — Brad Bourque, The Verge, 11 Nov. 2026

The long school holiday was coming to an end, and though the sunlight still offered the brightness of summer, the breeze that blew suggested the sombre quality of autumn. — Yasushi Inoue, New Yorker, 8 Nov. 2026

Moreover, each object in the apparent pairs of detections had to be about the right brightness and move the correct amount for a planet orbiting the Sun several hundred times farther out than Earth. — Phil Plait, Scientific American, 6 Nov. 2026

The brightness matters for HDR content, sure, but what really makes OLED stand out is per-pixel illumination—meaning each pixel can turn on or off independently. — ArsTechnica, 6 Nov. 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