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 aim of the telescopes was to provide continuous coverage of the sky from both the Northern and Southern hemispheres, using identical telescopes with adaptive optics and the capability to conduct near-infrared wide-field surveys. —Keith Cooper, Space.com, 26 Nov. 2025

Simply use the attachment with its red, amber, and infrared lights for three minutes on each area of your face (such as your forehead, nasolabial folds, and so on) to help smooth and firm, then swap it out for the microcurrent head and slick on some conductive gel to start tightening and toning. —Emily Orofino, Vogue, 26 Nov. 2025

There are traditional Finnish saunas (dry heat/steam), infrared saunas (radiant heat), Turkish baths/hammams (can include a venik ritual where guests are flogged with branches) and Russian banyas (high-humidity steam). —Eileen Falkenberg-Hull, MSNBC Newsweek, 26 Nov. 2025

Fill your days with nutrition and sleep consultations, yoga, meditation, stretching classes, and spa appointments inside your own private hale, equipped with an infrared sauna, an outdoor shower, and soaking pools. —Lydia Mansel, Travel + Leisure, 22 Nov. 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