United States

• federal department

  A department of the federal government of the United States.

• State Department

  A department of government in one of the 50 states.

Great Britain

• Special Branch

  A government police department dealing with political security.

• admiralty

  The department in charge of the navy (as in Great Britain).

Also contains

• local department

  A permanent department created to perform the work of a local government.

• ministry

  A government department under the direction of a minister.

• instrumentality

  A subsidiary organ of government created for a special purpose; "are the judicial...

• treasury

  The government department responsible for collecting and managing and spending public ...