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 automatically measures the distance between the edges of the folding panels, uses sensors to detect offsets and recalibrates the brightness of adjacent LEDs to hide the tiny slot. —New Atlas, 13 June 2026

Research has found that satellites and other orbiting objects could increase the overall brightness of the night sky by more than 10% above natural levels. —Jamie Carter, Forbes.com, 13 June 2026

How to Use Offbeat Green in Your Home Sherwin-Williams recommends using Offbeat Green as an accent color throughout your home, bringing brightness to your kitchen cabinets and warmth to your bedroom furniture. —Sophia Beams, Better Homes & Gardens, 13 June 2026

Ones with wide fields of view and sensitive detectors can easily spot these incoming bits of interplanetary jetsam and gather data on their brightness, size, speed and direction. —Phil Plait, Scientific American, 12 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