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[verb ih-rey-dee-eyt; adjective ih-rey-dee-it, -eyt] /verb ɪˈreɪ diˌeɪt; adjective ɪˈreɪ di ɪt, -ˌeɪt/
verb (used with object), irradiated, irradiating.
to shed rays of light upon; illuminate.
to illumine intellectually or spiritually.
to brighten as if with light.
to radiate (light, illumination, etc.).
to heat with radiant energy.
to treat by exposure to radiation, as of ultraviolet light.
to expose to radiation.
verb (used without object), irradiated, irradiating.
  1. to emit rays; shine.
  2. to become radiant.
irradiated; bright.
Origin of irradiate
1595-1605; < Latin irradiātus, past participle of irradiāre to shine upon. See ir-1, radiate
Related forms
irradiatingly, adverb
irradiative, adjective
irradiator, noun
nonirradiated, adjective
unirradiated, adjective
unirradiative, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for irradiate
Historical Examples
  • The prophetical books will aid the student, and the Psalms will irradiate certain dark periods.

  • Was it a reflection of that which should continue to irradiate it?

    A Veldt Vendetta Bertram Mitford
  • Fine feathers do not make fine birds, and yet the consciousness of a becoming gown will irradiate the cheek of beauty.

  • At that quite a new gleam seemed to irradiate his good-looking clay.

    The Story of Louie Oliver Onions
  • We returned the bow, allowing a polite smile to irradiate our countenance and answered Waleicoum salaam.

    At the Court of the Amr John Alfred Gray
  • The target may be any substance that the physicist or chemist wants to irradiate.

    LRL Accelerators Lawrence Radiation Laboratory
  • Suddenly thin yellow beams of sunshine began to penetrate and irradiate the thick white blanket of mist.

    The Angel Cyril Arthur Edward Ranger Gull
  • And the mere knowledge that he exists will irradiate the rest of mine.

    Erewhon Revisited Samuel Butler
  • Nancy frowned on, apparently plunged in thought, then slowly a flash seemed to irradiate her features.

    Etheldreda the Ready Mrs. George de Horne Vaizey
  • He had been intent on this prize from the first; but he had never allowed his eagerness to irradiate his refined face.

British Dictionary definitions for irradiate


(transitive) (physics) to subject to or treat with light or other electromagnetic radiation or with beams of particles
(transitive) to expose (food) to electromagnetic radiation to kill bacteria and retard deterioration
(transitive) to make clear or bright intellectually or spiritually; illumine
a less common word for radiate (sense 1)
(intransitive) (obsolete) to become radiant
Derived Forms
irradiative, adjective
irradiator, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for irradiate

c.1600, "to cast beams of light upon," from Latin irradiatus, past participle of irradiare "shine forth," from assimilated form of in- "into, in" (see in- (2)) + radiare "to shine" (see radiate). Meaning "expose to radiation other than light" (originally X-rays) is from 1901. Related: Irradiated; irradiating.

Online Etymology Dictionary, © 2010 Douglas Harper
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irradiate in Medicine

irradiate ir·ra·di·ate (ĭ-rā'dē-āt')
v. ir·ra·di·at·ed, ir·ra·di·at·ing, ir·ra·di·ates

  1. To expose to radiation, as for diagnostic or therapeutic purposes.

  2. To treat with radiation.

  3. To apply radiation to a structure or organism.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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irradiate in Science
To expose to or treat with radiation. For example, meat sold as food is often irradiated with x-rays or other radiation to kill bacteria; uranium 238 can be irradiated with neutrons to create fissionable plutonium 239.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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