The word "admiral" in Middle English comes from Anglo-French amiral, "commander", from
Medieval Latin admiralis, admirallus. These themselves come from
amīr", or amīr al- (أمير الـ), "commander of", as in amīr al-baḥr (أمير البحر), "commander of the sea".
 The term was in use for the
Greco-Arab naval leaders of
Norman Sicily, which had formerly been ruled by Arabs, at least by the early 11th century.
Roger II of Sicily (1095–1154), employed a Greek Christian known as
George of Antioch, who previously had served as a naval commander for several North African Muslim rulers. Roger styled George in
Abbasid fashion as "
Amir of Amirs", i.e. "Commander of Commanders", with the title becoming Latinized in the 13th century as "ammiratus ammiratorum".
Sicilians and later
Genoese took the first two parts of the term and used them as one word, amiral, from their
Aragon opponents. The
Spanish gave their sea commanders similar titles while in
Portuguese the word changed to almirante. As the word was used by people speaking
Latin or Latin-based languages it gained the "d" and endured a series of different endings and spellings leading to the English spelling "admyrall" in the 14th century and to "admiral" by the 16th century.