01 a. Lying outside the visible spectrum at its red end; -- said of rays having a longer wavelength (and thus less refrangible) than the extreme …
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1.
Lying outside the visible spectrum at its red end; -- said of rays having a longer wavelength (and thus less refrangible) than the extreme red rays, specifically those electromagnetic waves having a wavelength of between 700 nanometers and 1 millimeter.(Physics)
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2.
relating to, using, or producing infrared radiation.
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3.
affected by infrared radiation; as, infrared detector; infrared film.