Pirate Ships > Frigate
A frigate is a type of warship that comes in various sizes and was used many times throughout the Golden Age of Piracy as a type of pirate ship. During the 17th century and primarily the Buccaneering Era the term was used for any type of warship that was build for speed and maneuverability which was a great advantage in the West Indies. They were often smaller than a ship of the line but were larger than a brigantine or brig.
Often these warships would carry their main battery of cannons or carriage mounted guns on a single deck or on two decks with other guns such as swivel guns mounted on the forecastle and quarterdeck of the ship. They were considered fully rigged ships which contained three masts and square-rigging on each of them. Often these types of ships were used for patrolling or escorts instead of for intense Naval Warfare.
In a definition that was adopted by the British Admiralty they were considered ships that had 28 guns and had all of their primary weapons on a single continuous upper deck. In contrast, ships of the line would contain two continuous decks of cannons. Eventually the term would come to define a type of armored vessel throughout the 19th century but that is mostly outside of the scope of the types of ships used in the Post Spanish Succession Period and the Pirate Round.