The term 'Sail Extender' is a type of sailboat rigging that is used to increase the area of the sail. It is also known as a SPRIT, which is a five-letter word that can be found in crossword puzzles. The sail extender is a pole or spar that is attached to the mast and extends out over the sail, allowing for more wind to be captured and providing additional power to the boat. It is an important part of sailing and is used to increase the speed and maneuverability of the boat.