/ Dictionary / Index C cofunction: Meaning and Definition of Find definitions for: co•func•tion Pronunciation: (kō'fungk"shun), [key] — n. Trigonom. the function of the complement of a given angle or arc: cos&thgr; is the cofunction of sin&thgr;. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. C. of S. cog Related Content Daily Word Quiz: blithesome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language