Clerestory or clearstory
In architecture, this term (spelled either way) refers to a wall of a building which is raised above an adjoining room, and this section of wall has windows. The walls of the nave in a Christian church are higher than the roof over the side aisles, for example, and the clerestory contains windows for light and ventilation. Because of the heavy walls, the clerestory windows of a Romanesque church were small and admitted little light. Development of the pointed arch, piers, and flying buttresses in the Gothic cathedral made possible the enlargement of this window area.(pr. KLEER-stə-ree)Also see aisle, crocket, fenestration, glass, stained glass, and vault.