/ Dictionary / Index R radiotherapy: Meaning and Definition of Find definitions for: ra•di•o•ther•a•py Pronunciation: (rā"dē-ō-ther'u-pē), [key] — n. Med. treatment of disease by means of x-rays or of radioactive substances. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: radiotherapy (Thesaurus) radioteletype radiothermy Related Content Daily Word Quiz: profiterole Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language