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

Using infrared cameras, an airplane survey of 8000 industry sites found that 4% had unusually high methane emissions, most tied to hatches and vents in natural gas storage tanks at extraction wells. Warren Cornwall, Science | AAAS, "Natural gas could warm the planet as much as coal in the short term," 21 June 2018 This nonablative device offers two settings that can be used together or separately: One remodels and stimulates collagen growth deep in the dermis, using infrared light and radio frequency (RF). Allure, "The Skin-Care Glossary: A Comprehensive Guide to Everything You Need to Know," 17 Aug. 2018 On the plus side, the mask’s ample wraparound design includes infrared lights meant to treat wrinkles, sensors to track your heart rate and movement, and embedded headphones that pipe in audio-meditation and sleepy soundscapes. Rebecca Dolan, WSJ, "Trouble Sleeping? High-Tech Masks Can Help," 25 July 2018 The study team also detected the unique infrared-light signatures of nanodiamonds — carbon crystals far smaller than a grain of sand — in these same three systems, and nowhere else. Mike Wall,, "Puzzling Cosmic Glow Is Caused by Diamond Dust Glamming Up Stars," 11 June 2018 Professor Mukherjee says that photons from high-energy sources tend to get absorbed by infrared background radiation. Eoin O'carroll, The Christian Science Monitor, "Neutrino demonstration heralds a new way of observing the cosmos," 12 July 2018 Designing something that can prevent this, and can thus carry camouflage into the infrared, has proved tricky. The Economist, "How to fool infrared vision gear into thinking you are not there," 5 July 2018 Could near-infrared light be used to excite, or trigger neurons? Rob Reid, Ars Technica, "Ars on your lunch break, week 3: Mary Lou Jepsen on AI and spooky brain scans," 29 June 2018 The new solar window technologies, however, absorb almost exclusively invisible ultraviolet (UV) or infrared light. Robert F. Service, Science | AAAS, "Skyscrapers could soon generate their own power, thanks to see-through solar cells," 28 June 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

2 Dec 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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More from Merriam-Webster on infrared

Rhyming Dictionary: Words that rhyme with infrared

Spanish Central: Translation of infrared

Nglish: Translation of infrared for Spanish Speakers

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