Navy Department.A division of the Department of Defense that oversees the operation and efficiency of the Navy, including the Marine Corps component (and the U.S. Coast Guard when operating as a naval service). • Established in 1798, the Department is headed by the Secretary of the Navy, who is appointed by the President and reports to the Secretary of Defense. — Also termed Department of the Navy. [Cases: Armed Services 4. C.J.S. Armed Services §§ 14, 16–17, 19, 37.]

[Blacks Law 8th]