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 new generation of luxury retreats — places like Preidlhof, Sha Wellness and Velaa Private Island — now offer infrared therapy, cryotherapy, stem cell treatments, IV vitamin drips and biometric testing alongside the traditional spa menu. —Hanna Wickes, Kansas City Star, 22 May 2026

Ectoin supports the skin barrier and maintains hydration, while antioxidants phytoene and phytofluene protect against free-radical damage triggered by infrared exposure and environmental pollution. —Christa Joanna Lee, Allure, 22 May 2026

One video from a 2019 operation in the Middle East shows multiple unidentified objects captured by an infrared sensor. —Neetika Walter, Interesting Engineering, 22 May 2026

The inclusion of these, and of striking infrared shots turning the lush island greens blood red, and of still photography, all help fracture the toxic order (plus one conch) that had been holding the boys together. —Sarah Shachat, IndieWire, 20 May 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