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

From top to bottom, that means X-rays, ultraviolet, optical, infrared, and finally radio waves. —Andrew Paul, Popular Science, 26 June 2025

Recovery amenities include infrared saunas, hot and cold plunges and eucalyptus steam rooms. —Howard Cohen, Miami Herald, 25 June 2025

Unlike traditional wellness regimens, hers isn’t designed to optimize productivity or stoke desire; there are no infrared saunas or metabolic hacks. —Ellen O'Connell Whittet june 25, Literary Hub, 25 June 2025

This high-tech, full-coverage LED mask uses red, blue and infrared light therapy to target fine lines, acne and signs of aging. —Nora Colomer May Earn A Commission If You Buy Through Our Referral Links. This Content Was Created By A Team That Works Independently From The Fox Newsroom., FOXNews.com, 4 June 2025

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