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 chip routes multiple wavelengths, from ultraviolet to near-infrared light, needed to control the ion. — Neetika Walter, Interesting Engineering, 13 Nov. 2026

Guests can also book infrared sauna and salt therapy sessions. — Evan Moore november 13, Charlotte Observer, 13 Nov. 2026

To move, a lamp supplies it with flashes of energy, pulsing near-infrared light onto half a dozen liquid crystal muscles attached to a pair of hind legs. — New Atlas, 13 Nov. 2026

Mariner 9 carried four primary instruments to study Mars, including a camera system for imaging, an ultraviolet spectrometer, an infrared spectrometer and an infrared radiometer. — Tariq Malik, Space.com, 13 Nov. 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