/ Dictionary / Index P plenum ventilation: Meaning and Definition of Find definitions for: ple'num ventila"tion Pronunciation: [key] a system of mechanical ventilation in which fresh air is forced into the spaces to be ventilated from a chamberat a pressure slightly higher than atmospheric pressure, so as to expel foul air. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. plenum pleo- Related Content Daily Word Quiz: fervor Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language