/ Dictionary / Index C complex plane: Meaning and Definition of Find definitions for: com'plex plane' Pronunciation: [key] — Math. Math. a plane the points of which are complex numbers. Cf. Argand diagram. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. complexometry complex sentence Related Content Daily Word Quiz: resilient Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language