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

Its infrared search and track data fed directly into an onboard AI agent that controlled the X-62A and guided it into tactical intercept positions. — Aamir Khollam, Interesting Engineering, 4 Aug. 2026

Under the lid are four stainless steel grates, six infrared burners and stainless heat diffusers, and a stainless steel upper rack. — John R. Delaney, PC Magazine, 4 Aug. 2026

In the new study, the researchers analyzed near-infrared light from those inner moons using the James Webb Space Telescope . — Charles Q. Choi, Space.com, 3 Aug. 2026

These images of the corona and solar prominences were taken in different wavelengths of visible and infrared light by imagers aboard a NASA’s WB-57 jet during the April 8, 2024, total solar eclipse. — Jamie Carter, Forbes.com, 1 Aug. 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