Imperial presidency
Arthur M. Schlesinger Jr. popularized the term "imperial presidency" during the Nixon administration in his 1973 book "Imperial presidency". The term implies the self-imposed rule by one leader or emperor within a constitutionally established government. Most would consider the U.S.A. government to be democratically controlled, but it is the constitution’s 3 branches (Executive, Judicial, and Legislative) that create and impose the of constitutionally upheld rule law. Though the U.S.A. is considered a democracy because it's constitution is a living document, malleable and changeable according to the interest of a democratically elected congress.
While only the Congress and Administrative branches are democratically elected by its legal voting citizens, the inclusion of all its people such as women, slaves, indentured servants, and men who didn't own land was only made possible 121 years after the Constitution came into force in 1789. This excludes the voter Rights Act of 1965.