from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Of or relating to the range of invisible radiation wavelengths from about 750 nanometers, just longer than red in the visible spectrum, to 1 millimeter, on the border of the microwave region.
  • adj. Generating, using, or sensitive to infrared radiation.
  • n. Infrared light or the infrared part of the spectrum.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • 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 the wavelength in the infrared.

from the GNU version of the Collaborative International Dictionary of English

  • adj. 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.
  • adj. relating to, using, or producing infrared radiation.
  • adj. affected by infrared radiation.

from The Century Dictionary and Cyclopedia

  • Below the red.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. having or employing wavelengths longer than light but shorter than radio waves; lying outside the visible spectrum at its red end
  • n. the infrared region of the electromagnetic spectrum; electromagnetic wave frequencies below the visible range
  • n. electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves


from Wiktionary, Creative Commons Attribution/Share-Alike License

Latin infra, below, + red


  • Anyone who understands chemistry also knows that carbon dioxide is a gas that transmits visible light, but attempts to retain infrared radiation.

    An Inconvenient Truth | My[confined]Space

  • And here, made with the 31-inch telescope at UVa's Fan Mountain in the infrared, is M51:

    Archive 2008-12-30

  • I bet he sees everything in infrared like the Predator, too.


  • Yep, the greenhouse effect works because light in the visible spectrum passes through “greenhouse” gases, while reradiated infrared is absorbed.

    Matthew Yglesias » Green Roofs

  • Because the Predator can “sparkle” a target at night — mark it in infrared so that A-10 pilots and grunts on the ground can see it with their night-vision goggles — it opens up a range of options that pilots and infantry never had before.

    Hunting the Taliban in Las Vegas

  • A spectacular satellite image of Alaska's Malaspina Glacier in infrared, near infrared, and green wavelengths.

    Archive 2006-05-01

  • Essentially, the badges have 4 LED lights that light up when you get within infrared range of other attendees with similar profiles.

    Archive 2005-09-01

  • A spiral galaxy resembling our own - NGC 7331 in infrared, from Spitzer

    Our Twin

  • (In the lab prototype, the video camera, with its built-in infrared beam, serves as the camera detector, while the projector is the neutralizer.)

    System ‘blinds’ digi-cams

  • It's explicit and erotic, but the choice to shoot in infrared transforms the human bodies onscreen into incandescent, glass-like forms.

    Boing Boing: January 5, 2003 - January 11, 2003 Archives


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  • All Italian verbs end in -re. Although the past participle would be something like infratto, assuming it had a regular conjugation. But anyway we can go ahead and make a plausible nonsensical sentence, thus:

    Con la nuova macchina fotografica digitale, mi viene la voglia di infrare.

    - With my new digital camera I get the urge to take infrared photographs.

    I don't know why I bothered to do that but it was quite satisfying.

    November 19, 2009

  • For quite a while when young I supposed this to be the past tense of infrare. Infrared rays...I still see it! Similarly, I thought it very possible to misle someone.

    November 19, 2009