The term "three-master" is commonly used to describe a large sailing ship that has three masts. However, there are several synonyms for this term that can be used to describe similar types of ships. One such synonym is "trireme," which was a type of ancient Greek or Roman warship with three levels of oars. Another synonym is "barquentine," which is a sailing vessel with three masts where only the foremast and mainmast are square-rigged. A "schooner" is another type of three-masted sailing ship that has two masts that are taller than the third, giving it a distinctive appearance. Lastly, a "clipper" is a swift-sailing vessel that has three masts and was commonly used for trade or mail transport in the 19th century.