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

Unmanned Aerial Systems with thermal imaging and infrared capability are in use and night-capable aircraft are available to support crews overnight if needed and as conditions permit. —Ca Wildfire Bot, Sacbee.com, 8 Sep. 2025

The spa features biohacking treatments, exclusive beautifying therapies by high-end Hungarian brand Omorovicza, and a series of outdoor baths and infrared saunas. —Siobhan Reid, Travel + Leisure, 8 Sep. 2025

The temperature has to be so low that atoms emit no infrared radiation, rendering traditional thermal imaging ineffective. —Atharva Gosavi, Interesting Engineering, 8 Sep. 2025

Open your camera app to spot infrared lights. —Kurt Knutsson, FOXNews.com, 8 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