- \ \  Admirals originally had nothing specifically to do with the sea. The word comes ultimately from Arabic ’amīr ‘commander’ (from which English later also acquired emir ). This entered into various titles followed by the particle -al- ‘of’ (’amīr-al-bahr ‘commander of the sea’, ’amīr-al-mūminīn ‘commander of the faithful’), and when it was borrowed into European languages, ’amīr-al- became misconstrued as an independent, free-standing word. Moreover, the Romans, when they adopted it, smuggled in their own Latin prefix ad-, producing admiral. When this reached English (via Old French) it still meant simply ‘commander’, and it was not until the time of Edward III that a strong naval link began to emerge. The Arabic title ’amīr-al-bahr had had considerable linguistic influence in the wake of Arabic conquests around the Mediterranean seaboard (Spanish almirante de la mar, for instance), and specific application of the term to a naval commander spread via Spain, Italy, and France to England. Thus in the 15th century England had its Admiral of the Sea or Admiral of the Navy, who was in charge of the national fleet.\ \ By 1500 the maritime connection was firmly established, and admiral came to be used on its own for ‘supreme naval commander’.\ \ Cf.⇒ EMIR
Word origins - 2ed. J. Ayto. 2005.