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

Blue light targets acne-causing bacteria to help keep breakouts at bay, while red and near-infrared wavelengths penetrate deeper to stimulate collagen, improve circulation, and promote skin repair. —Conçetta Ciarlo, Vogue, 1 Oct. 2025

Psyche’s next-gen laser communication tests On November 14, 2023, the Psyche spacecraft successfully beamed a message back to Earth via infrared laser for the first time. —Chris Young, Interesting Engineering, 30 Sep. 2025

Following his disappearance, officers immediately commenced a multi-agency search involving more than 200 people, dogs, drones, infrared cameras and search teams on the ground and in the air. —Sam Gillette, PEOPLE, 29 Sep. 2025

New state-of-the-art wellness tech was also added, like a hyperbaric oxygen pod and an infrared sauna. —Kathryn Romeyn, Travel + Leisure, 28 Sep. 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