/ Dictionary / Index A API: Meaning and Definition of Find definitions for: API Pronunciation: [key] American Petroleum Institute. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. aphyllous Apia Related Content Daily Word Quiz: penurious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language