argosy n.

1570s, "large merchant vessel carrying rich freight," from Italian (nave) Ragusea "(vessel) of Ragusa," maritime city on the Dalmatian coast of the Adriatic (modern Dubrovnik in Croatia). Their large merchant ships brought rich Eastern goods to 16c. England. The city name sometimes was Aragouse or Arragosa in 16c. English. Figurative use from 1620s.