Department of the Navy
The executive part of the Department of the Navy at the seat of government; the headquarters, US Marine Corps; the entire operating forces of the United States Navy and of the US Marine Corps, including the Reserve Components of such forces; all field activities, headquarters, forces, bases, installations, activities, and functions under the control or supervision of the Secretary of the Navy; and the US Coast Guard when operating as a part of the Navy pursuant to law. Also called DON. See also Military Department.
Dictionary of Military and Associated Terms. US Department of Defense 2005.