ar·chi·pel·a·go / ˌärkəˈpeləˌgō/ • n. (pl. -gos or -goes) a group of islands. ∎ a sea or stretch of water containing many islands.ORIGIN: early 16th cent.: from Italian arcipelago, from Greek arkhi- ‘chief’ + pelagos ‘sea.’ The word was originally used as a proper name (the Archipelago ‘the Aegean Sea’): the generalization of meaning occurred because the Aegean Sea is remarkable for its large numbers of islands.
the Greek islands in the Aegean Sea, hence, any sea or broad sheet of water containing many islands.
Examples: archipelago of isolated communities, 1862; of the Polar Ocean, 1830.