U.S. Army, U.S. Marine Corps the noncommissioned officer, usually a master sergeant, serving as chief administrative assistant to the commander of a company, battery, etc.
The senior noncommissioned officer of a US Army or Marine Corps unit, who is equivalent in rank to a master sergeant and performs administrative duties.
(plural first sergeants)
- (US) In the United States Army, a non-commissioned officer ranking above sergeant first class and below sergeant major; equal in rank to a master sergeant but with greater command authority.
- (US) In the United States Marine Corps, a non-commissioned officer ranking above gunnery sergeant and below sergeant major or master gunnery sergeant; equal in rank to a master sergeant, but with command rather than technical responsibilities.
- (US) In the United States Air Force, an appointment (not a rank) for the senior member of enlisted personnel in a squadron or other unit. The appointment is usually held by a master sergeant.