The term 'Nave Endings' refers to the architectural feature of a church or cathedral, which is the rounded end of the central aisle of the building. The crossword solution 'apses' (5 letters) is another term for this feature, which is also known as an apse arch. An apse is a semicircular recess in the wall of a church, typically at the east end, containing the altar and often flanked by two towers.