An abat-son is any architectural device designed to reflect sound in a particular direction, usually taking the form of louvers that direct the sound of bells from a belfry toward the ground.
abacus (capital component)abaci
In an architectural context, an abacus is the rectangular slab along the top of a column capital, often left plain but sometimes decoratively carved.
An ambulatory is a covered passage around and behind an altar, linking it with chapels at the east end of a church.
An apse is a rounded alcove or extension, usually at the east end of a church.
An arcade is a row of arches supported on piers or columns. They may be used to support vaults, divide interiors (such as nave and side aisles in a church), articulate walls (such as blind arches on facades), or create a portico.
An archivolt is the exposed face or molding of an arch, arranged concentrically and often decoratively carved.
barrel vaultbarrel vaults
A barrel vault is a vault shaped like half a barrel, which runs the length of the nave and has no rib vaults. Most commonly seen in early medieval buildings.
A basilica is a type of building, or a status of a church, or both. Architecturally, a basilica is an oblong, colonnaded building that was used in the Roman Empire as a town hall or law court. The style was adapted by early Christianity in its church architecture. In its other meaning, a basilica is a church that has been awarded special status by the Pope.
A bay is a vertical section of a nave, usually marked by vertical shafts or supporting columns at its four corners and arches on each side.
A belfry is the upper story of a tower where bells are hung, or a purpose-built structure for the hanging of bells.