/ Dictionary / Index A acorn tube: Meaning and Definition of Find definitions for: a'corn tube" Pronunciation: [key] — Electronics. Electronics. a vacuum tube, resembling an acorn in size and shape, used chiefly in ultrahigh-frequency electronic devices. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. acorn sugar acorn worm Related Content Daily Word Quiz: labyrinth Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language