| the Chiefs of Staff of the Army and the Air Force, the commandant of the Marine Corps, and the Chief of Naval Operations, together with a chairman selected from one of the branches of the armed forces, serving as the principal military advisory body to the President, the National Security Council, and the Secretary of Defense. |
Joint Chiefs of Staff  (joint)  n. 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. |
A high-level military advisory board in the Department of Defense, composed of high-ranking representatives of the army, navy, air force, and marines. The Joint Chiefs are responsible for formulating military policy and recommending action regarding issues of national security and international relations.