/ Dictionary / Index E ef-: Meaning and Definition of Find definitions for: ef- Pronunciation: [key] var. of (by assimilation) before f: efficient. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. eery eff. Related Content Daily Word Quiz: procrastinate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language