/ Dictionary / Index P plane geometry: Meaning and Definition of Find definitions for: plane' geom'etry Pronunciation: [key] — Math. Math. the geometry of figures whose parts all lie in one plane. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. plane angle plane iron 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