Noun
A projecting part of a building, esp. of a church, having in the plan a polygonal or semicircular termination, and, most often, projecting from the east end. In early churches the Eastern apse was occupied by seats for the bishop and clergy.
The bishop's seat or throne, in ancient churches.
Source: Webster's dictionaryAccording to chronicler Leo of Ostia the Greek artists decorated the apse, the arch and the vestibule of the basilica. Source: Internet
Gaudí intended that a visitor standing at the main entrance be able to see the vaults of the nave, crossing, and apse; thus the graduated increase in vault loft. Source: Internet
At the south-east corner there is a larger semi-circular projection which accommodates the apse of the chapel. Source: Internet
Christ in Majesty was a common theme for the apse. Source: Internet
Flanking the apse and east end of the nave were side chambers serving as sacristies; further porticus might continue along the nave to provide for burials and other purposes. Source: Internet
He includes a detailed description of the apse mosaic over the main altar and gives the text for a long inscription he had written to be put on the wall under the image. Source: Internet