transept

noun

1. The transversal part of a church, which crosses at right angles to the greatest length, and between the nave and choir. In the basilicas, this had often no projection at its two ends. In Gothic churches these project greatly, and should be called the arms of the transept. It is common, however, to speak of the arms themselves as the transepts.

   “Here, in the transept and choir, where the service was being held, one was conscious every moment of an increasing brightness; colours glowing vividly beneath the circular chandeliers, and the rows of small lights on the choristers' desks flashed and sparkled in front of the boys' faces, deep linen collars, and red neckbands.”