Wiki article on this topic: Sultan is a position with several historical meanings. Originally, it was an Arabic abstract noun meaning "strength", "authority", "rulership", derived from the verbal noun سلطة sulṭah, meaning "authority" or "power". Later, it came to be used as the title of certain rulers who claimed almost full sovereignty in practical terms , albeit without claiming the overall caliphate, or to refer to a powerful governor of a province within the caliphate. The adjective form of the word is "sultanic", and the dynasty and lands ruled by a sultan are referred to as a sultanate.
The term is distinct from king , despite both referring to a sovereign ruler. The use of "sultan" is restricted to Muslim countries, where the title carries religious significance, contrasting the more secular king, which is used in both Muslim and non-Muslim countries.
A feminine form of sultan, used by Westerners, is Sultana or Sultanah and this title has been used legally for some Muslim women monarchs and sultan's mothers and chief consorts. However, Turkish and Ottoman Turkish also uses sultan for imperial lady, as Turkish grammar—which is influenced by Persian grammar—uses the same words for both women and men. However, this styling misconstrues the roles of wives of sultans. In a similar usage, the wife of a German field marshal might be styled Frau Feldmarschall. The female leaders in Muslim history are correctly known as "sultanas". However, the wife of the sultan in the Sultanate of Sulu is styled as the "panguian" while the sultan's chief wife in many sultanates of Indonesia and Malaysia are known as "permaisuri", "Tunku Ampuan", "Raja Perempuan", or "Tengku Ampuan". The queen consort in Brunei especially is known as Raja Isteri with the title of Pengiran Anak suffixed, should the queen consort also be a royal princess.
In recent years, "sultan" has been gradually replaced by "king" by contemporary hereditary rulers who wish to emphasize their secular authority under the rule of law. A notable example is Morocco, whose monarch changed his title from sultan to king in 1957.