What is President Of The United States?

Legal Definition
The President of the United States (POTUS) is the elected head of state and head of government of the United States. The president directs the executive branch of the federal government and is the commander-in-chief of the United States Armed Forces.

The President is considered to be one of the world's most powerful political figures, as the leader of the only contemporary global superpower. The role includes being the commander-in-chief of the world's most expensive military with the second largest nuclear arsenal and leading the nation with the largest economy by nominal GDP. The office of President holds significant hard and soft power both in the United States and abroad.

Article II of the U.S. Constitution vests the executive power of the United States in the president. The power includes execution of federal law, alongside the responsibility of appointing federal executive, diplomatic, regulatory and judicial officers, and concluding treaties with foreign powers with the advice and consent of the Senate. The president is further empowered to grant federal pardons and reprieves, and to convene and adjourn either or both houses of Congress under extraordinary circumstances. The president is largely responsible for dictating the legislative agenda of the party to which the president is a member. The president also directs the foreign and domestic policy of the United States. Since the office of President was established in 1789, its power has grown substantially, as has the power of the federal government as a whole.

The president is indirectly elected by the people through the Electoral College to a four-year term, and is one of only two nationally elected federal officers, the other being the Vice President of the United States. The Twenty-second Amendment (adopted in 1951) prohibits anyone from being elected president for a third term. It also prohibits a person from being elected to the presidency more than once if that person previously had served as president, or acting president, for more than two years of another person's term as president. In all, 44 individuals have served 45 presidencies (counting Grover Cleveland's two non-consecutive terms separately) spanning 57 full four-year terms. On January 20, 2017, Donald Trump was sworn in as the 45th and current president.
-- Wikipedia
Legal Definition
The official title of the chief executive officer of the federal government in the United States.
-- Black's Law Dictionary