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The Collaborative International Dictionary

Infrared \In`fra*red"\, Infra-red \In`fra-red"\, a. [Infra- + red.]

  1. (Physics) 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.

  2. relating to, using, or producing infrared radiation.

  3. affected by infrared radiation; as, infrared detector; infrared film.


a. 1 Having the wavelength in the infrared. 2 In the infrared spectrum. n. electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation, having a wavelength between 700 nm and 1 mm


adj. 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"

  1. n. the infrared part of the electromagnetic spectrum; electromagnetic wave frequencies below the visible range; "they could sense radiation in the infrared" [syn: infrared frequency]

  2. electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves [syn: infrared light, infrared radiation, infrared emission]


Infrared (IR) is invisible radiant energy, electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum at 700 nanometers ( frequency 430 THz) to 1 mm (300 GHz) (although people can see infrared up to at least 1050 nm in experiments). Most of the thermal radiation emitted by objects near room temperature is infrared.

Infrared radiation was discovered in 1800 by astronomer Sir William Herschel, who discovered a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect on a thermometer. Slightly more than half of the total energy from the Sun was eventually found to arrive on Earth in the form of infrared. The balance between absorbed and emitted infrared radiation has a critical effect on Earth's climate.

Infrared energy is emitted or absorbed by molecules when they change their rotational-vibrational movements. Infrared energy excites vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for study of these energy states for molecules of the proper symmetry. Infrared spectroscopy examines absorption and transmission of photons in the infrared energy range.

Infrared radiation is used in industrial, scientific, and medical applications. Night-vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected. Infrared astronomy uses sensor-equipped telescopes to penetrate dusty regions of space such as molecular clouds, detect objects such as planets, and to view highly red-shifted objects from the early days of the universe. Infrared thermal-imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, and to detect overheating of electrical apparatuses.

Thermal-infrared imaging is used extensively for military and civilian purposes. Military applications include target acquisition, surveillance, night vision, homing, and tracking. Humans at normal body temperature radiate chiefly at wavelengths around 10 μm (micrometers). Non-military uses include thermal efficiency analysis, environmental monitoring, industrial facility inspections, remote temperature sensing, short-ranged wireless communication, spectroscopy, and weather forecasting.

Infrared (record label)

Infrared is a UK-based drum and bass record label owned by J Majik.

Infrared (disambiguation)

Infrared is electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum.

Infrared may also refer to:

  • Infrared spectroscopy, a subset of spectroscopy
  • Consumer infrared, as used in wireless remote controls, keyboards, and other devices
  • Infrared (record label), a UK-based record label
  • "Infra-Red" (song), by Placebo

Usage examples of "infrared".

The light source covers infrared and all of the visible spectrum, not, repeat not, monochromatic.

They were greeted by Desis One and Two, who flanked a long coffee table on which there were four MAC-10 machine pistols, twenty magazine clips, sixteen grenades, four miniaturized radios, two flamethrowers, four infrared binoculars, and a dismantled egg-shaped bomb that could blow up at least a quarter of the state of New Hampshire - the lesser southeastern part.

But with heat sensors, sound sensors, visual apparatus, infrared scanners, encephalographic trackers, and a complete library of card indices on every public act you and I have engaged in, they have no room for weapons.

Infrared Photography by Shuco-Mist Medical Pressure Systems, Enfield MA.

A large one, homeothermic, to judge from the infrared, holding still a short ways off.

From another pocket of the utility vest he took the Metascope, the night-vision monocular that detected infrared light, and put it to his right eye.

All you needed was an orbit twenty kilometres above the Ring plane, where you could watch for the infrared signature of reaction drives as scavenger craft matched orbits with their chosen shell sections.

The phone was equipped for e-mail, of course, but he was old-fashioned and he made the infrared connections to the Thinkpad and dialed up the Peoria AOL access number.

The hot surface reradiates energy as infrared, which cannot get through the atmosphere.

The illuminated spot expanded and reradiated in the infrared spectrum.

But since the Earth is a lot cooler than the Sun, this energy is reradiated not at ultraviolet wavelengths but at the much longer infrared, to which the atmosphere is not as transparent.

When he scanned around with his retinal insets on infrared the geometric buildings were a uniform temperature.

Not only is there X-ray analysis, spectrography, infrared, and all the rest.

The energy for his little ecosystem came from his armor, for he had adjusted the outer plates to radiate in the infrared, and draped the whole affair in a thermophilic fungus organism like pale seaweed, to photosynthesize heat energy and start the simple food chain.

These structures masked the exhaust emissions of the twin turboshaft engines and shielded them from the infrared sensors of hostile missiles.