The elements of the word are Greek, but there is no record of arkhipelagos in ancient or Medieval Greek (the modern word in Greek is borrowed from Italian), so the word perhaps is an Italian compound or an alteration in Italian of Medieval Latin Egeopelagus, from Greek Aigaion pelagos "Aegean Sea." The Aegean being full of island chains, the meaning was extended in Italian to "any sea studded with islands" (a sense attested in English from c. 1600) and to the islands themselves. Related: Archipelagian; archipelagic.
1660s, name of a cowardly braggart (supposed by some to represent a Spanish don) in traditional Italian comedy, from Italian Scaramuccia, literally "skirmish," from schermire "to fence," from a Germanic source (such as Old High German skirmen "defend"); see skirmish (n.). According to OED, a vogue word in late 17c. London due to the popularity of the character as staged there by Italian actor Tiberio Fiurelli (1608-1694).