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

Powered by a blend of nourishing antioxidants, this lightweight formula offers superior protection from UVA, UVB, and infrared rays while boosting your skin’s defense against pollution and blue light. —Kiana Murden, Vogue, 10 Mar. 2025

The gym includes saunas, infrared heat, and virtual fitness instructors. —Talia McWright, Twin Cities, 10 Mar. 2025

Other studies on infrared light, which has a longer wavelength of at least 800 nanometers that penetrates deeper into the skin, suggest that there's potential for the treatment to speed up muscle recovery. —Bailey Schulz, USA TODAY, 8 Mar. 2025

The results generated hundreds of wavelength measurements across the infrared light spectrum that McCarthy’s team could analyze for changes over the course of its speedy rotation. —Andrew Paul, Popular Science, 5 Mar. 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