infrared

adjective

in·​fra·​red ˌin-frə-ˈred How to pronounce infrared (audio)
-(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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
These properties offer multiple benefits over infrared light systems, which are used in modern optical communication systems. — Muskan Bhatia, Interesting Engineering, 30 Oct. 2026 Researchers also collected 12-hour baseline air measurements in participants’ bedrooms and used micro-Fourier transform infrared spectroscopy to identify the size and chemical composition of airborne particles. — Alexandra Harrell, Footwear News, 29 Oct. 2026 The area of Ice Mountain and other nearby peaks were heavily searched by aircraft, including multiple drones and helicopters, as well as aircraft with infrared technology. — Jennifer McRae, CBS News, 28 Oct. 2026 As part of their regular recovery routine, many Brigham Young University players are wearing headsets that shine near-infrared light onto their scalps — and up their noses. — Lynne Peeples, New York Times, 28 Oct. 2026 See All Example Sentences for infrared

Word History

First Known Use

1881, in the meaning defined at sense 1

Time Traveler
The first known use of infrared was in 1881

Phrases Containing infrared

Rhymes for infrared

See All Rhymes for infrared

Browse Nearby Words

infra praesidia
infrared
infrared lamp
See all Nearby Words

Cite this Entry

“Infrared.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/infrared. Accessed 1 Nov. 2026.

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Kids Definition

infrared

adjective
in·​fra·​red ˌin-frə-ˈred How to pronounce infrared (audio)
-(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 How to pronounce infrared (audio)
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
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