[ih-rey-dee-ey-shuh n]
See more synonyms for irradiation on
  1. the act of irradiating.
  2. the state of being irradiated.
  3. intellectual or spiritual enlightenment.
  4. a ray of light; beam.
  5. Optics. the apparent enlargement of an object when seen against a dark background.
  6. the use of x-rays or other forms of radiation for the treatment of disease, the making of x-ray photographs, the manufacture of vitamin D, etc.
  7. exposure or the process of exposure to x-rays or other radiation.
  8. Physics. irradiance.

Origin of irradiation

First recorded in 1580–90, irradiation is from the Late Latin word irradiātiōn- (stem of irradiātiō). See ir-1, radiation
Related formspost·ir·ra·di·a·tion, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for irradiation

Contemporary Examples of irradiation

Historical Examples of irradiation

  • The phenomena of magnetism were ascribed by him to the irradiation of angels.

  • The force of the irradiation has been directly proportional with the squares of the distances.


    Edgar A. Poe

  • However, is it not interesting to attribute the apparent movement to irradiation?

    Visual Illusions

    Matthew Luckiesh

  • That was charming and vivacious, and his smile was an irradiation.

    Crome Yellow

    Aldous Huxley

  • "Excuse me," he said with an irradiation of smiles, but yet with a kind of bewilderment.

    The Ball and The Cross

    G.K. Chesterton

British Dictionary definitions for irradiation


  1. the act or process of irradiating or the state of being irradiated
  2. the apparent enlargement of a brightly lit object when it is viewed against a dark background
  3. a shaft of light; beam or ray
  4. med
    1. the therapeutic or diagnostic use of radiation, esp X-rays
    2. exposure of a patient to such radiation
  5. another name for radiation, irradiance
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

Word Origin and History for irradiation

1580s, from French irradiation, from Latin *irradiationem, noun of action from past participle stem of irradiare (see irradiate). Originally of light (literally and figuratively); of X-rays, etc., from 1901.

Online Etymology Dictionary, © 2010 Douglas Harper

irradiation in Medicine


  1. Exposure or subjection to the action of radiation for diagnostic or therapeutic purposes.
  2. Medical treatment by exposure to radiation.
  3. The spread of a nervous impulse beyond the usual path of conduction.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.