/ Dictionary / Index P positive column: Meaning and Definition of Find definitions for: pos'itive col"umn Pronunciation: [key] — Physics. Physics. the luminous region between the Faraday dark space and the anode glow in a vacuum tube, occurring when the pressure is low. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. positive caster positive crankcase ventilation Related Content Daily Word Quiz: cygnet Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language