AISLE, in architecture, a term primarily meaning the wing of a house, but more commonly used to indicate any long, narrow space separated from the remainder of the building by a line of piers, columns or arches. It is specially used to designate the lateral portions of a church or other large room in which interior supports occur. The term also has come to tnean a passageway, specially a passageway between groups of seats, as in a church or theatre. From the time of the early Christian basilica, the use of one or more side aisles flanking a central nave has been al most universal in church building, and church aisles are known as nave aisles, transept aisles or choir aisles from their position in relation to the nave, transept or choir. The choir aisle around the east end of a choir is known as an ambulatory (q.v.). In the normal Romanesque or Gothic church the roof of the aisles is lower than the central nave ; but in certain examples in southern France (e.g., St. Nazaire, Carcassonne), in Spain (e.g., Barcelona), and especially in Germany, where for the smaller churches it is almost normal, the nave and aisles are of the same height. A church with nave flanked by one aisle on each side is known as a three-aisle church ; one with two side aisles on each side as a five-aisle church, and so on.