aisle
Τhe part of the naos of a church set off by the internal rows of piers or columns, namely by the structures supporting the roof.

ambo
The elevated pulpit used for preaching in the church nave.

ambulatory (byz. arch.)
A continuous passage that envelops the naos or the centrally planned core of a structure. In a cross-domed church, where the dome is supported on four masonry piers and between each pair of piers two columns are inserted, the ambulatory is formed by the lateral aisles and western part of the church. Later on, an ambulatory could also envelop a cross-in-square core. During the Palaeologan period, ambulatories, usually serving as funerary chambers, were added to many middle-Byzantine churches of Constantinople.

apse
An arched srtucture or a semi-circular end of a wall. In byzantine architecture it means the semicircular, usually barrel-vaulted, niche at the east end of a basilica. The side aisles of a basilica may also end in an apse, but it is always in the central apse where the altar is placed. It was separated from the main church by a barrier, the templon, or the iconostasis. Its ground plan on the external side could be semicircular, rectangular or polygonal.

atrium
1. Antiquity: The large, open space within a building, which is envelopped by colonnades.2. Βyzantium: The forecourt of a church in early Christian, Byzantine, and medieval arcitecture. It was usually surrounded by four porticoes (quadriporticus).

basilica
In ancient Roman architecture a large oblong type building used as hall of justice and public meeting place. The roman basilica served as a model for early Christian churches.

chancel screen of presbytery
A short barrier between the bema and the nave. It had originally the form of a parapet that was later made of stone or of marble. It is generally an element of early Christian religious architecture, and it appears on ground plans either as a linear structure or forming a Π. It consists of small columns or pillars in the interspace of which slabs are inserted. Crosses and floral patterns are usually used for the relief decoration of the screen.

coffer
Recessed ornamental square or octagonal panels sunk in the ceilings of buildings. They were decorated with relief or pictorial, usually floral, designs.

cross-domed basilica
Type of domed basilica. A church plan, whose core, enveloped on three sides by aisles and galleries with a transept, forms a cross. The core is surmounted by a dome in the centre.

dome
A characteristic element of Byzantine architecture. The dome is a hemispherical vault on a circular wall (drum) usually pierced by windows. The domed church emerges in the Early Byzantine years and its various types gradually prevail, while they are expanded in the Balkans and in Russia.

entablature, the
The upper part of the classical order, that rests on the columns, it consists of the architrave, frieze and cornice.

gallery
The upper level of a house where the women resided. In ecclesiastical architecture it is the corridor above the aisles and narthex of a church, from where women attended the Liturgy. Originally (in the Byzantine period) the gallery, having a special entrance, was used exclusively by the emperor and the members of the royal family.

marble revetment
Τhe facing of a wall with slabs of marble

narthex
A portico or a rectangular entrance-hall, parallel with the west end of an early Christian basilica or church.

Panel
low wooden or stone closure, often with bas-relief decorations, e.g. marble panel in Byzantine churches closing the openings at the lower part of screens and between the columns of the side aisles.

pendentive
Triangular surface used for the transition from the square base of the church to the hemispheric dome.

porch
The covered space at the front of a gate on the building's entrance or a stoa.

semi-dome
The vaulted crown of an apsed niche. The semi-dome of the apse of the Bema may be also called a conch.

skeuophylakion
(‘Treasure house’ or sacristy) A particular area or room in the churches for keeping vestments and the church furnishings, sacred vessel. Usually take place in the diakonikon, south (at right) from the central apse with the altar.

solea
A wide and oblong elevated passageway in front of the central opening of the chancel screen that reached until the ambo; there stood the deacons and the lectors during the Service.

synthronon
Rows of built benches, arranged in a semicircular tier like a theatre, in the apse of a church. On these benches the clergy sat during Divine Liturgy. The bishop sat on the cathedra at the top of the synthronon.

three-aisled basilica
An oblong type of church internally divided into three aisles: the middle and the two side aisles. The middle aisle is often lighted by an elevated clerestory. In the Early Byzantine years this type of church had huge dimensions.