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

Webb is designed to observe primarily infrared light, which is especially good at revealing dust, cool-to-warm gas, and star formation regions that can be hidden in visible-light images. —Kenna Hughes-Castleberry, Space.com, 8 Jan. 2026

Current trackers often rely on infrared cameras that can cause eye strain over time. —Mrigakshi Dixit, Interesting Engineering, 7 Jan. 2026

Boxing studios — Rumble, 9Round, neighborhood gloves-on gyms — fill in the edges, while recovery bars, cold plunges and infrared saunas make post-class feel as intentional as the work itself. —Eric Barton, Sun Sentinel, 4 Jan. 2026

An information card at Pause said benefits of infrared sauna contrast therapy can include boosting metabolism, skin health, elevating immunity, athletic and physical recovery, heart health and pain management. —Heidi Finley, Charlotte Observer, 2 Jan. 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