The word archipelago is derived from the Italian arcipelago, used as a proper name for the Aegean Sea, itself perhaps a deformation of the Greek Αιγαίον Πέλαγος.
The erudite paretymology deriving the word from Ancient Greek ἄρχι-(arkhi-, "chief") and πέλαγος (pélagos, "sea"), proposed by Buondelmonti, can still be found here and there.
Continental fragments are islands that were once part of a continent, and became separated due to natural disasters.
The fragments may also be formed by moving glaciers which cut out land, which then fills with water.
The islands of the Inside Passage off the coast of British Columbia and the Canadian Arctic Archipelago are examples.