/ Dictionary / Index R radio knife: Meaning and Definition of Find definitions for: ra'dio knife" Pronunciation: [key] — Surg. Surg. an electrical instrument for cutting tissue that by searing severed blood vessels seals them and prevents bleeding. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. radioisotope radiolabel Related Content Daily Word Quiz: portent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language