A galleon was a large, multi-decked sailing ship used as an armed cargo carrier primarily by European states during the age of sail from the 16th to 18th centuries and were the principal fleet units drafted for use as warships until the Anglo-Dutch wars of the mid-1600s. Galleons generally carried three or more masts with a lateen fore-and-aft rig on the rear masts, were carvel built with a prominent squared off raised stern, and used square-rigged sail plans on their fore-mast and main-masts. Such ships were the mainstay of maritime commerce into the early 19th century, and were often drafted into use as auxiliary naval war vessels—indeed, were the mainstay of contending fleets through most of the 150 years of the Age of Exploration — before the Anglo-Dutch wars begat purpose-built ship-rigged warships that thereafter dominated war at sea during the remainder of the Age of Sail.
The term Galleon "large ship", comes from Old French Galion "little ship" (13c.), from Spanish (Castilian) Galeón "armed merchant ship", from Portuguese Galeão "war ship", from Byzantine Greek Galea "galley" + augmentative suffix -on. Another possible origin is the Old French word galie meaning "galley;" also from Byzantine Greek galea. The galea was a warship of the Byzantine navy, and its name may be related to the Greek word galeos, "dogfish shark". The term was originally given to certain types of war galleys in the Middle Ages. The Annali Genovesi mentions galleons of 80, 64 and 60 oars, used for battle and on missions of exploration, in the 12th and 13th centuries. It is very likely that the galleons and galliots mentioned in the accounts of the crusades were the same vessels. In the early 16th century, the Venetian galleoni was a new class of galley used to hunt down pirates in the Mediterranean.