/ Dictionary / Index B beam-power tube: Meaning and Definition of Find definitions for: beam'-pow•er tube" Pronunciation: (bēm'pou"ur), [key] — Radio. Radio. a vacuum tube in which the stream of electrons flowing to the plate is focused by the action of a set of auxiliary, charged elements, giving an increase in output power. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Beamon beam reach Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language