Apse

Apse (pronounced aps)

(1) In architecture, a semicircular or polygonal termination or recess in a building, usually vaulted and used especially at the end of a choir in a church.

(2) The bishop's seat or throne in ancient churches.

(3) A reliquary (or case) in which the relics of saints were kept.

(4) In astronomy, an alternative name for an apsis (either of two points in an eccentric orbit, one (higher apsis) farthest from the centre of attraction, the other (lower apsis) nearest to the center of attraction); largely obsolete.

1815–1825; A variant of apsis & hapsis, from the Ancient Greek ἁψίς (hapsís) (arch, vault), from ἅπτω (háptō) (I bind, join) from haptein (to fasten).  The Ancient Greek ἁψίς (hapsís) (from the Ionic apsis) originally meant "a fastening, felloe of a wheel," from haptein (fasten together) which is of unknown origin. The original sense in Greek seems to have been the joining of the arcs to form a circle, especially in making a wheel.  As an architectural term, it’s attested in English (in the Latin form) as early as 1706. Apse is a noun, apsidal is an adjective and apsidally is an adverb; the noun plural is apses.  

A more familiar derivation of haptein was the noun synapse (junction between two nerve cells), an 1899 creation of medical Latin, from the Greek synapsis (conjunction), from or related to synaptein (to clasp, join together, tie or bind together, be connected with), the construct being syn- (together) + haptein (to fasten).  It was introduced by English physiologist Charles Sherrington (1857-1952), summarizing recent work by other neurologists, in an 1897 revision of Sir Michael Foster's (1836–1907) Textbook of Physiology; the form of the coinage suggested by the English classical scholar Arthur Woollgar Verral (1851-1912).

The cathedra (bishop's chair) of Rome, in the apse in the Basilica of St John Lateran, Rome.