from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A military officer who, for a given day, assumes responsibility for security, order, and supervision of the guard.
from the GNU version of the Collaborative International Dictionary of English
- n. the officer who, on a given day, has charge for that day of the guard, prisoners, and police of the post or camp; abbreviated O. D., OD, or O. O. D.
Sorry, no etymologies found.