Aisles: The sides of the church's nave separated from the central nave by a row of columns.
Ambo: The elevated pulpit used for preaching in the church nave.
Ambulatory: A walkway circumventing the sanctified part of the church.
Ampulla (pl. ampullae): A small flask, made of lead, clay, or other material, containing sanctified liquid (water, oil) from Christian shrines.
Anastasios I: Byzantine emperor (491-518). He is known for his devotion to the Monophysitism and for this he had a hard opposition by the Orthodox. Due to Anastasios an extent programm of fiscal reformation took place in the last decade of the 5th century. On the eastern and northern borders of the state he had to confront the raids of the Persians and the Bulgarians. Probably it was Anastasios who ordered the construction of the long wall in Thrace, in ca. 503/4.
Anchorite: A hermit monk.
Anicia Juliana: Descendant of Theodosios II and Eudocia, member of the wealthy patrician family of the Anicii. Juliana used her wealth to construct churches, monasteries and philanthropic institutions. She financed the construction of St Polyeuktos on the site of an earlier church erected by Eudocia.
Apse: Semicylindrical conch, at the eastern side of the church, designated for the clergy. It was separated from the rest of the church by means of a screen or gratings.
Arianism: the teachings of Arius, an Alexandrian priest, who argued that God the Father and Jesus Christ were two separate beings, and that, therefore, within a monotheist concept, Christ could not be divine. Arianism was condemned by the first Ecumenical Council (Nicaea, 325), which held God and Christ to be one, the latter having a dual (both human and divine) nature.
Arkadios: Byzantine emperor (395-408). In the period of his reign he had to confront in the Balkans the Visigoths, under Alaric, and the Huns, and in Asia Minor the revolt of the Isaurians. The defeat of the "Gothic party" and its leader, the usurper Gainas, was probably the theme of the sculptural decorated column, erected by Arkadios in the Hippodrome of Constantinople, in 400.
Asceticism: The exercise of mind and body is the ideal for all Christians, especially for monks and that is why asceticism is a synonym for monasticism. The first ascetics made their appearance in the 3rd century at the desert of Egypt (e.g. St Anthony), who were called hermits or anchorites. The ascetics in order to develop self-discipline submitted their body to many ordeals the chief forms of which was fasting.
Atrium: The forecourt of a church, usually located at the western end of the building and surrounded by stoas.