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

Most display ultraviolet light, indicating stars, plus optical/infrared light, indicating active black holes. —Big Think, 20 Oct. 2025

The glasses’ camera captures visual scenes and projects them as an infrared beam across the chip. —Aamir Khollam, Interesting Engineering, 20 Oct. 2025

Because of that, infrared saunas typically run at lower temperatures and are easier for some people to tolerate. —Brigitt Earley, Glamour, 20 Oct. 2025

Sunlighten has become the go-to brand in the infrared sauna space, mostly due to the quality and customizability of its products. —Dean Stattmann, Outside, 19 Oct. 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