Meaning

noun the supreme commander of a fleet; ranks above a vice admiral and below a fleet admiral

noun any of several brightly colored butterflies

originFrom Middle English admiral etc., from Anglo-Norman and Old French admiral etc., from Medieval Latin admiralis, admirallus, and admiralius, from irregular modification of amiralis etc. under the influence of the prefix ad- and particularly admiror (“to admire, respect”), from Arabic أَمِير (ʔamīr, “commander”) + -alis (“-al”). The ending is frequently but mistakenly folk etymologized to derive…

Etymology from Wiktionary, CC BY-SA 3.0