/ Dictionary / Index C complementary angle: Meaning and Definition of Find definitions for: com'plemen'tary an'gle Pronunciation: [key] — Math. Math. either of two angles that added together produce an angle of 90°. Cf. supplementary angle. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. complementary complementary base Related Content Daily Word Quiz: sumptuous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language