Noncommissioned Officer
Noncommissioned Officer, or NCO (also called Noncom), in military service, an enlisted man or woman holding a rank that gives him or her authority over other enlisted personnel. NCO's hold the rank of corporal or sergeant. Their rank, in the armed forces of most countries, is indicated by chevrons, which are worn on the sleeve or, sometimes, the collar. Naval services use the term petty officer instead of noncommissioned officer.