in·fra·red | \ˌin-frə-ˈred, -(ˌ)frä-, -fə-\

Definition of infrared 

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

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Other Words from infrared

infrared noun

Examples of infrared in a Sentence

Recent Examples on the Web

The airport is also considering technology to detect intruders, such as infrared motion detection or radar sensors that can trigger an alarm if someone climbs a fence. Kelly Yamanouchi, ajc, "Fence jumpers highlight security vulnerability at Hartsfield-Jackson," 12 July 2018 The tests, using an infrared microscope, showed a global average of 10.4 plastic particles per liter. Frank Kummer,, "Are you drinking tiny plastics in that bottled water?," 15 Mar. 2018 To ensure that the painting was not a forgery, Descharnes also spent nine months searching through archives and conducting tests, including infrared photography and signature and pigment analysis. Brigit Katz, Smithsonian, "Rediscovered Salvador Dalí Painting Goes on Display," 1 Mar. 2018 But fire itself wasn’t fully quantifiable until the past couple decades, when Department of Defense scientists perfected infrared cameras that allowed them to shoot explosions at 1,000 images per second. Kyle Dickman, Outside Online, "What the West Can Learn from Florida About Forest Fires," 27 June 2018 Additionally, James Webb will take observations primarily in infrared, while GMT is optimized for light in the visible spectrum. Jay Bennett, Popular Mechanics, "The Deep Space Eye in the Desert," 14 Feb. 2018 That yields strong heat-resistant rolls that are sliced thin to be used as coverings or windows protecting infrared targeting systems and other sensors on military equipment. Paul Brinkmann,, "Vibration from Orlando City Stadium construction damaged high-tech business next door, lawsuit says," 31 May 2018 In order to take pictures in infrared, the ABI needs to be at approximately -350℉. This is very cold, and in order to reach such a low temperature the ABI needs a functioning cooling system. Avery Thompson, Popular Mechanics, "NOAA's New Weather Satellite Has a Cooling Problem," 25 May 2018 Using a 26-foot Gemini North telescope, the team of scientists studied the reflected sunlight in infrared and determined what types of molecules made up the planet's atmosphere, the release said. The Washington Post,, "Planet Uranus smells of flatulence, rotten eggs, scientists say," 24 Apr. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'infrared.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of infrared

1881, in the meaning defined at sense 1

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Statistics for infrared

Last Updated

7 Oct 2018

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Time Traveler for infrared

The first known use of infrared was in 1881

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More Definitions for infrared



English Language Learners Definition of infrared

: producing or using rays of light that cannot be seen and that are longer than rays that produce red light


in·fra·red | \ˌin-frə-ˈred \

Kids Definition of infrared

: being, relating to, or producing rays like light but lying outside the visible spectrum at its red end


in·fra·red | \ˌin-frə-ˈred \

Medical Definition of infrared 

(Entry 1 of 2)

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



Medical Definition of infrared (Entry 2 of 2)

: infrared radiation

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Comments on infrared

What made you want to look up infrared? Please tell us where you read or heard it (including the quote, if possible).


exaggeratedly or childishly emotional

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