/ Dictionary / Index P phi-function: Meaning and Definition of Find definitions for: phi-func•tion Pronunciation: (fī'fungk"shun), [key] — n. Math. See Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Phidippides Phil Related Content Daily Word Quiz: opulent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language