Meaning of officer of the day

of'ficer of the day'

Pronunciation: [key]
— Mil. Mil.
  1. 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.