chief of staff
- the head member of the staff officers of a division or higher unit in the armed forces, or of the Departments of the Army or Air Force
- the head of any staff; esp., the head of the physicians and surgeons of a hospital
See chief of staff in American Heritage Dictionary 4
noun pl. chiefs of staff Abbr. C. of S.
- The ranking officer of the U.S. Army or Air Force, responsible to the secretary of his or her branch and to the President.
- The senior military staff officer at the division level or higher.