/ Dictionary / Index I irradiation: Meaning and Definition of Find definitions for: ir•ra•di•a•tion Pronunciation: (i-rā"dē-ā'shun), [key] — n. the act of irradiating. the state of being irradiated. intellectual or spiritual enlightenment. a ray of light; beam. the apparent enlargement of an object when seen against a dark background. 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. exposure or the process of exposure to x-rays or other radiation. irradiance. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: irradiation (Thesaurus) irradiate irradicable Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language