The term 'OLD WAR SHIP' can be solved by the crossword solution 'FRIGATE', which is a seven-letter word. Frigates were originally used as warships during the Age of Sail, from the 16th to the 19th centuries. They were typically square-rigged vessels with three masts and a full bowsprit. Frigates were used for patrolling, convoy escort, and commerce raiding, and were also used as flagships in larger fleets.