Pl. apses. [ad. L. apsis: cf. basis, base, axis, axe, etc. See APSIS.]
1. Arch. A semi-circular or polygonal recess, arched or dome-roofed, in a building, esp. at the end of the choir, aisles or nave of a church. Cf. APSIS 3.
1846. in Parker, Concise Gloss. Arch.
1849. Freeman, Archit., 155. The altar was placed at the end of the nave, on the chord of the apse.
1876. M. Davies, Unorth. Lond., 329. Behind this, occupying the apse, was an organ.
2. Astr. = APSIS 2.
1822. Imison, Sc. & Art, II. 427. The two points in a planets orbit furthest and nearest to the body round which it moves, are called the apses, or apsides.
1879. Lockyer, Elem. Astron., ix. xlix. 307. The apses, or extremities of the major axisthe aphelion or perihelion points.