/ Dictionary / Index O officer of the day: Meaning and Definition of Find definitions for: of'ficer of the day' Pronunciation: [key] — Mil. Mil. an officer who has charge of the guard and prisoners on an assigned day at a military installation. Abbr.: OD, O.D., O.O.D. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. officer of arms officer of the deck Related Content Daily Word Quiz: cur Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language