/ Dictionary / Index R radio tube: Meaning and Definition of Find definitions for: ra'dio tube" Pronunciation: [key] a vacuum tube used in a radio receiving set. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. radiotransparent radiovision Related Content Daily Word Quiz: morose Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language