a group within the Department of Defense, consisting of the Chief of Staff of the Army, the Chief of Naval Operations, the Chief of Staff of the Air Force, the Commandant of the Marine Corps, a director, and a chairman
See Joint Chiefs of Staff in American Heritage Dictionary 4
noun Abbr. JCS
The principal military advisory group to the President of the United States, composed of the chiefs of the Army, Navy, and Air Force and the commandant of the Marine Corps.