[verb ih-rey-dee-eyt; adjective ih-rey-dee-it, -eyt]

verb (used with object), ir·ra·di·at·ed, ir·ra·di·at·ing.

verb (used without object), ir·ra·di·at·ed, ir·ra·di·at·ing.

  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 formsir·ra·di·at·ing·ly, adverbir·ra·di·a·tive, adjectiveir·ra·di·a·tor, nounnon·ir·ra·di·at·ed, adjectiveun·ir·ra·di·at·ed, adjectiveun·ir·ra·di·a·tive, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for irradiate

light, lighten, brighten

Examples from the Web for irradiate

Historical Examples of irradiate

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

    A Veldt Vendetta

    Bertram Mitford

  • The glory of the greatest of her children will for ever irradiate her and the whole world.

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

    The Story of Louie

    Oliver Onions

  • Deeper than tears, these irradiate the tophets with their glad heavens.


    Amos Bronson Alcott

  • The target may be any substance that the physicist or chemist wants to irradiate.

    LRL Accelerators

    Lawrence Radiation Laboratory

British Dictionary definitions for irradiate



(tr) physics to subject to or treat with light or other electromagnetic radiation or with beams of particles
(tr) to expose (food) to electromagnetic radiation to kill bacteria and retard deterioration
(tr) to make clear or bright intellectually or spiritually; illumine
a less common word for radiate (def. 1)
(intr) obsolete to become radiant
Derived Formsirradiative, adjectiveirradiator, 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

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

irradiate in Medicine




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

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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.