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 extrasolar planet, or exoplanet, under the watchful infrared eye of the JWST, is WASP-17b, located around 1,300 light-years away. — Robert Lea, Space.com, 16 Oct. 2026

Rectal thermometers are preferred for children 3 and under; oral and digital infrared thermometers are both fine choices for anyone older than that. — Andee Tagle, NPR, 15 Oct. 2026

Laser codes create individual fuel records After inspection, each pebble moves to an infrared laser engraving station. — Kaif Shaikh, Interesting Engineering, 15 Oct. 2026

After exploring or relaxing by the pool, head to the freestanding infrared sauna with optional salt halotherapy. — Condé Nast, Condé Nast Traveler, 13 Oct. 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