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 rocky planet's exceptional brightness is a side effect of its dense atmosphere, which veils the planet's surface beneath dense sulphuric acid clouds that reflect 70% of incoming sunlight back out into space, according to MIT. — Anthony Wood, Space.com, 18 Sep. 2026

MiniLED is becoming a more practical choice for everyday home entertainment, offering the kind of brightness, contrast, and picture control that once felt limited to models with a considerable price tag. — New Atlas, 16 Sep. 2026

While the telescope’s Galactic Bulge survey is designed to primarily search for microlensing events, Roman will also repeatedly measure the brightness of hundreds of millions of stars along the way. — Thomas Fauchez, The Conversation, 14 Sep. 2026

Astronomers first argued that little red dots were distant galaxies on the cosmic horizon, mainly because of their brightness. — Quanta Magazine, 14 Sep. 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