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

Then, firefighters with hand tools and infrared technology checked the area for heat. —Richard Winton, Los Angeles Times, 31 Jan. 2026

Red light, for example, has decent research about the antiaging impact of near-infrared LED lights that penetrate a few millimeters of skin. —Sandee Lamotte, CNN Money, 31 Jan. 2026

LightPath is now marketing germanium-free infrared cameras to customers, and Moeller added said existing infrared cameras may be converted to BlackDiamond glass too. —Davis Giangiulio, CNBC, 29 Jan. 2026

It’s equipped with infrared tracking sensors, secure communication systems, and flexible payload bays that can be configured for weapons, electronic warfare tools, surveillance gear, or decoy equipment, depending on the mission. —Atharva Gosavi, Interesting Engineering, 29 Jan. 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