/ Dictionary / Index H heptode: Meaning and Definition of Find definitions for: hep•tode Pronunciation: (hep'tōd), [key] — n. Electronics. a vacuum tube containing seven electrodes, usually a plate, a cathode, a control electrode, and four grids. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. heptavalent heptose Related Content Daily Word Quiz: resilient Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language