what is the leader of each department called
The heads of the executive departments receive the title of Secretary of their respective department, except for the Attorney-General who is head of the Justice Department (and the Postmaster General who until 1971 was head of the Post Office Department). The heads of the executive departments are appointed by the President and take office after confirmation by the United States Senate, and serve at the pleasure of the President. The heads of departments are members of the Cabinet of the United States, an executive organ that normally acts as an advisory body to the President. In the Opinion Clause (Article II, section 2, clause 1) of the U.S. Constitution, heads of executive departments are referred to as "principal Officer in each of the executive Departments".