The term 'APSE' is a four letter word that refers to the semicircular part of a church. An APSE is typically located at the eastern end of a church and is often used as a place for the altar or other religious artifacts. It is also commonly used as a place for the clergy to stand during services. The APSE is an important architectural feature in many churches and is often decorated with mosaics, frescoes, or other artwork.