/ Dictionary / Index P phlogiston: Meaning and Definition of Find definitions for: phlo•gis•ton Pronunciation: (flō-jis'ton, -tun), [key] — n. a nonexistent chemical that, prior to the discovery of oxygen, was thought to be released during combustion. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: phlogiston (Thesaurus) phlogistic phlogopite 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