INFRARED

adj. pertaining to the invisible electromagnetic radiation situated outside of the visible red end of the spectrum

Infrared (IR) radiation is  electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means "below red" (from the Latin infra, "below"), red being the color of visible light with the longest wavelength. Infrared radiation has wavelengths between about 750 nm and 1 mm, spanning five orders of magnitude.
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Noun
1. the infrared part of the electromagnetic spectrum; electromagnetic wave frequencies below the visible range; "they could sense radiation in the infrared"
(synonym) infrared frequency
(hypernym) frequency, frequence, oftenness
(part-holonym) infrared spectrum
2. electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves
(synonym) infrared light, infrared radiation, infrared emission
(hypernym) actinic radiation, actinic ray
Adjective
1. having or employing wavelengths longer than light but shorter than radio waves; lying outside the visible spectrum at its red end; "infrared radiation"; "infrared photography"
(similar) invisible, unseeable

The region of the electromagnetic spectrum bounded by the long-wavelength extreme of the visible spectrum (approximately 0.7 m) and the shortest microwaves (approximately 0.1 mm).

<electronics> (IR) Electromagnetic waves in the frequency range just below visible light corresponding to radiated heat. IR waves can be generated by a kind of LED and are often used for remote controls for televisions etc. and in some docking stations.
(1997-01-30)