/ Dictionary / Index U U.S.A.F.: Meaning and Definition of Find definitions for: U.S.A.F. Pronunciation: [key] United States Air Force. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: usaf (Thesaurus) usable USAFI Related Content Daily Word Quiz: censure Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language