puhekieltä A semicircular projection from a building, especially the rounded east end of a church that contains the altar.
1960, Leo Steinberg, San Carlo Alle Quattro Fontane: A Study in Multiple Form and Architectural Symbolism
The draughtsman could not have held the sheet with the apse at the tip, for then, instead of shading away from the edge, most of his hatched lines would begin in the uncharted middle ground of a shadeable area, to strike against the contour; (..)