infrared

adjective

in·​fra·​red ˌin-frə-ˈred 

-(ˌ)frä-, 

-fə-

1

: situated outside the visible spectrum at its red end

—used of radiation having a wavelength between about 700 nanometers and 1 millimeter

2

: relating to, producing, or employing infrared radiation

infrared therapy

3

: sensitive to infrared radiation

infrared sensors that detect body heat

infrared noun

Examples of infrared in a Sentence

Recent Examples on the Web

The James Webb Space Telescope captures infrared images, which cannot be seen by the human eye, and spectra to spread light out to reveal chemical fingerprints. —Kierra Frazier, CBS News, 19 June 2026

The cocooning experience of infrared bed therapy uses red and infrared light to support skin health and reduce inflammation. —Alexandra Kirkman, Forbes.com, 19 June 2026

For very remote galaxies, however, redshifting stretches even that extreme UV light into infrared wavelengths. —Phil Plait, Scientific American, 19 June 2026

For body recovery, joint pain or full-body wellness, panels delivering 660nm red plus 850nm near-infrared cover the most use cases. —Allison Palmer, Miami Herald, 18 June 2026

Word History

First Known Use

1881, in the meaning defined at sense 1

Phrases Containing infrared

• far-infrared
• near-infrared

Rhymes for infrared

• abovesaid
• aforesaid
• arrowhead
• casinghead
• copperhead
• figurehead
• fountainhead
• gingerbread
• hammerhead
• leatherhead
• letterhead
• loggerhead

Kids Definition

infrared

adjective

in·​fra·​red ˌin-frə-ˈred 

-(ˌ)frä-

: being, relating to, producing, or using rays like light but lying outside the visible spectrum at its red end

infrared radiation

infrared noun

Medical Definition

infrared

1 of 2 adjective

in·​fra·​red ˌin-frə-ˈred 

1

: lying outside the visible spectrum at its red end

—used of radiation having a wavelength between about 700 nanometers and 1 millimeter

2

: relating to, producing, or employing infrared radiation

infrared therapy

infrared

2 of 2 noun

: infrared radiation