Amir al-Mu'minin (; latinized as , hence Italian , French , Spanish  and Portuguese , in Byzantine Greek: amermoumnês), usually translated "Commander of the Faithful" or "Leader of the Faithful", is the Arabic style of Caliphs and other independent sovereign Muslim rulers that claim legitimacy from a community of Muslims. It has been claimed as the title of rulers in Muslim countries and empires and is still used for some Muslim leaders. It is also translated as "Prince of the believers" since "Amir" or "Emir" is also used as a princely title in states ruled by the royalty or monarchies.