Amīr al-Mu'minīn (Arabic أمير المؤمنين; latinized as Miramolinus, hence Italian Miramolino, Spanish Miramolín and Portuguese Miramolim, in Byzantine Greek: ἀμερμουμνῆς amermoumnes) 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 also means "Prince of the believers" when it is translated from Arabic into English.

• http://en.wikipedia.org/wiki/Amir al-Mu'minin
• Page 184 - Montefiore, S., 2011, Jerusalem: the Birography: Vintage Books, New York, 650p.