Architecturally the central, open space of a church, west of the choir or chancel, and separated therefrom by a low wall or screen. It is divided from the side aisles by columns, shafts, or piers, is roofed with timber or vaulted in masonry, and usually rises above the level of the aisle roofs to provide high windows for lighting. Colloquially, the term is used to indicate that portion of a church reserved for worshippers, and including the central and side aisles, crossing transepts. The name is derived from the Latin navis, a ship, possibly with some reference to the "ship of St. Peter" or the Ark of Noah. The norm of all subsequent developments, whether early Christian, Byzantine, Norman, Medieval, or Renaissance, is to be found in the Roman basilica, with its wide, central area, and its aisles and galleries separated therefrom by columns and arches supporting the upper walls, pierced by windows, and the timber roof. During the third and fourth centuries the apse, which in the classical examples immediately terminated the central opened space, was pushed back and separated from the nave proper by a transverse nave or transept; later the junction of nave, transept, and apse (now prolonged into a deep choir or chancel) was surmounted by a dome, or tower, the space below being called the crossing, while the simple system of equal supports equally spaced was for a time abandoned for the alternating system. Simultaneously the upper walls were increased in height, the aisles vaulted in masonry, the nave itself; the solids were reduced to a minimum in favour of windows that tended ever to increase in size, the space above the aisle vaults and their sloping roofs was arcaded and thrown open to the nave, a complete system of buttress was devised and perfected, and the complete Gothic nave came into existence (see GOTHIC ARCHITECTURE). Except in the smallest churches the nave was flanked by an aisle on each side, sometimes (e.g. in Bourges Cathedral) by double aisles. Occasionally, as in the Jacobean churches of the thirteenth century, there were two naves side by side, of equal dimensions and separated by screens; occasionally also, particularly in Germany and Flanders, nave and aisles were of equal height. The standard type, however, was that of the lofty nave with arcade, triforium, and clerestory, flanked by a comparatively low aisle on each side.

In early Christian basilicas the sanctuary was hardly more than a semicircular apse, the transept or transverse nave serving for clergy and choir: little by little the chancel was deepened to accommodate the increasing number of clerics, but the transept and crossing were still shut off from the people's nave. As monasticism developed, more and more of this portion of the church was enclosed, until in many Cistercian abbey churches the entire central space from east to west was reserved. In the south of Europe the enclosed choir still frequently projects far to the west of the crossing; but in France, in the great cathedrals of the Middle Ages, nave, transepts and crossing were cleared, the choir screen being fixed at the eastern side of the crossing, and this arrangement is, in modern times, almost universal. During the Middle Ages also, the great development of preaching necessitated an even greater space for the congregation, and as a result the medieval nave increased to vast proportions and was capable of holding crowds that often numbered tens of thousands. Nor were these vast auditoriums reserved exclusively for religious services; in many cases they were unconsecrated, and were used not only for miracle plays, but for many strictly secular purposes. The line between chancel and nave was always very clearly drawn: in England, for example, the parish priest had full authority in the former, and was bound to keep it in repair at his own expense, while the parish itself was responsible for the care and maintenance of the nave.

Ralph Adams Cram.