TRANSEPT ( from Lat. trans. across, through + septum, swptum, inclosure, parti tion; connected with swpcs, hedge). The pro jecting wings at right angles with the nave and aisles, forming the smaller arms of the cross, in the ground plan of churches. In some of the largest early basilicas it was placed at the very top, helping to form a T-plan. In such churches the great arch opening from the nave into the transept was called the triumphal arch. When the strictly cruciform plan was introduced for churches in the early Middle Ages (Carolingian period) the transept became quite common, and in the Gothic age. almost universal. It shows sometimes in plan, when it projects beyond the line of the side aisles; sometimes only in eleva tion, when, though not projecting. it is marked by its vault and roof, which intersect the lower roof of the aisles on a level with that of the nave.
The intersection is often called the crossing, and was usually surmounted by a spire, tower, o• dome, to mark it. The crossing was also usually marked by numb heavier piers.
While single transepts were the rule, there were two kinds of double transepts used in Eng land and Germany. The double English tran sept was on the scheme of the archbishop's or Passion cross, with both arms toward the choir end; the double German transept was connected with the double choir, one at each end of the church. The ends of the transepts in Gothic churches were often treated as facades only second in importance to the main front, with their large rose or wheel windows and their elaborate portals. Those of the Notre Dame in Paris, of Chartres, and Amiens are particularly beautiful.