In architecture, the apse (Greek αψις (apsis), then Latin absis: "arch, vault"; sometimes written apsis; plural apses) is a semicircular recess covered with a hemispherical vault or semi-dome. In Romanesque, Byzantine and Gothic Christian abbey, cathedral and church architecture, the term is applied to a semi-circular or polygonal termination of the main building at the liturgical east end (where the altar is), regardless of the shape of the roof, which may be flat, sloping, domed, or hemispherical.

The apse is the semicircular or polygonal termination to the choir or aisles of a church. In relation to church architecture it is generally the name given to where the altar is placed or where the clergy are seated.

The epithet "apsidal" may be applied to the exedra of classical architecture, a feature of the secular Roman basilica.

The apse as a semicircular projection (which may be polygonal on the exterior, or reveal the radiating projections of chapels) may be roofed with a semi-dome (also called a half-dome) or with radiating vaulting. A simple apse may be merely embedded within the wall of the east end. Eastern orthodox churches may have a triple apse, which is usually a mark of Byzantine influence when it is seen in Western churches.

Ståle Sandbech (born June 3, 1993) is a Norwegian snowboarder, from the town of Rykkinn in Bærum, Norway. He competes for the club BSK Snowboard, and Norges Toppidrettsgymnas of Geilo (NTG). He represented Norway at the 2010 Winter Olympics in Vancouver, and was the youngest Norwegian to go to the Olympics in 82 years.