King is the title given to a male monarch in a variety of contexts. A king is an absolute monarch if he holds the powers of government without control, or the entire sovereignty over a nation; he is a limited monarch if his power is restrained by fixed laws; and he is an absolute, when he holds the whole legislative, judicial, and executive power, or when the legislative or judicial powers, or both, are vested in other people by the king.
https://en.wikipedia.org/wiki/King