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

Similarly, pyrometers and aerospace instrumentation can require durable optical windows that allow infrared or other optical measurements while protecting sensitive internal components from harsh external conditions. — Prabhat Ranjan Mishra, Interesting Engineering, 17 Sep. 2026

The Foward Gauss Hidden Camera Detector is a great option, too, recommended by a former FBI agent and features an infrared laser detector that shoppers say can accurately detect camera lenses in the dark. — Julia Morlino, Travel + Leisure, 17 Sep. 2026

Following the successful activation of its infrared sensors, engineers moved on to calibrate the WFI's element wheel, which filters individual wavelengths for detection using a system of prisms and other optic mechanisms. — Josh Dinner, Space.com, 16 Sep. 2026

And everything has a different relationship with infrared light. — Georg Szalai, HollywoodReporter, 9 Sep. 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