/ Dictionary / Index N ninety-day wonder: Meaning and Definition of Find definitions for: nine'ty-day won'der Pronunciation: (nīn'tē-dā"), [key] — Informal. Informal. an officer commissioned in a branch of the armed forces after an unusually short training period, esp. after a three-months officers' training course during World War II. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ninety ninety-eight Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language