from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Architecture An apse.
- n. Astronomy The point of greatest or least distance of the orbit of a celestial body from a center of attraction.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A recess or projection, with a dome or vault, at the east end of a church; an apse.
- n. Either of the points in the elliptical orbit of a planet or comet where it is closest or furthest from the sun; perihelion or aphelion; an apside
from the GNU version of the Collaborative International Dictionary of English
- n. One of the two points of an orbit, as of a planet or satellite, which are at the greatest and least distance from the central body, corresponding to the aphelion and perihelion of a planet, or to the apogee and perigee of the moon. The more distant is called the higher apsis; the other, the lower apsis; and the line joining them, the line of apsides.
- n. In a curve referred to polar coördinates, any point for which the radius vector is a maximum or minimum.
- n. Same as Apse.
from The Century Dictionary and Cyclopedia
- n. In astronomy, a point in the eccentric orbit of a planet in which it is either furthest from or nearest to the body about which it revolves.
- n. In architecture, same as apse.
- n. A reliquary or case in which the relies of saints are kept, especially one of a form imitating the curves of a dome or vault.
- n. Sometimes written absis.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a domed or vaulted recess or projection on a building especially the east end of a church; usually contains the altar
In the apsis was a mosaic which represented the Blessed Trinity, and of which in 1512 some remnants were still found.
The presbytery was also known as apsis, exedra, concha, designations referring to its form; bema from the fact that it was elevated above the level of the nave and in consequence reached by a stairway of a few steps; tribuna because of its location and general resemblance to the tribunal in civil basilicas whence the magistrates administered justice.
This original church was modelled after the ancient Basilica, or hall of justice or of commerce: at one end was an elevated tribunal, and back of this what was called the "apsis," -- a rounded space with arched roof.
The east choir with the 1830s high altar; the rather interesting apsis painting was added in 1928:
Preliminary, it seems that we are dealing with a Roman settlement, followed by a (early) Byzantine use of the site, during which period at least one church was erected (cf. inscription by a deacon called Zosimos, who dedicated a door to a church, the apsis of which was found in situ nearby).
Urban VIII; On an ancient and interesting Christian sarcophagus taken from the Vatican cemetery is represented a basilica with its apsis, and near it a circular building evidently meant for the baptistery: this is covered with a cupola surmounted by the monogram of
When this apsis, therefore, of Mars shall appear in Virgo, who shall expect less than a strange catastrophe of human affairs in the commonwealth, monarchy, and kingdom of England?
The mosaics in the apsis are much restored, but they are the only known work of Cimabue,  and are consequently, even in their present condition, valuable and interesting.
It is variously designated apsis or concha (from the shell-like, hemispherical dome), and since the Middle Ages especially it has been called "choir", from the choir of singers who are here stationed.
Nola, Fondi, etc. The basilica at Nola counted five naves and had on each side four additions or chapels (cubicula), and an apsis arranged in a clover shape.