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 idea is that once the missile has been sighted, the laser counters it with a multi-spectral infrared laser that's powerful enough to dazzle and even destroy the missile's sensors. —New Atlas, 20 July 2025

Combined with timelapse recording capabilities, Roman will help researchers to better understand exoplanets, infrared astrophysics, and the nature of dark matter. —Andrew Paul, Popular Science, 17 July 2025

Only a short distance away on the same peak is the Gemini South telescope, which also looks at the stars in both visible and infrared wavelengths. —Kenna Hughes-Castleberry, Space.com, 14 July 2025

Radio wave wavelengths are much longer than infrared, so beamforming is more difficult. —Meghie Rodrigues, IEEE Spectrum, 12 July 2025

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