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

In the image below, Chandra's X-ray data was combined with infrared light gathered by the James Webb Space Telescope to help visualize the luminous shell of gas in reds, whites and blues. — Brett Tingley, Space.com, 1 July 2026

Phase-change materials that manage temperature by absorbing or releasing heat, infrared fibers and coatings, and advanced moisture-wicking technologies are also part of this innovation landscape. — Arthur Zaczkiewicz, Footwear News, 30 June 2026

Roman will pair a large field of view with crisp infrared vision to survey deep, vast swaths of sky. — Richard Tribou, The Orlando Sentinel, 29 June 2026

In the Mandara Spa & Salon on new vessels like Norwegian Luna and Norwegian Aqua, those include an infrared sauna that uses lamps to warm the body, a Floatation Salt Pool, and a charcoal sauna that reaches between 86 and 122 degrees – a facility the line bills as the first of its kind at sea. — Nathan Diller, USA Today, 28 June 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