This page provides definitions and illustrations of structural and ornamental and features and furnishiings within a church.

Terms related to Columns or Piers.

Capital — Topmost part of a column that provides the connection to the weight that is bearing down upon it.
Pier — Column or upright support for an arch or vaulted ceiling.
Entablature — Decorative horizontal structure that rests on top of a set of columns connecting them together.
Colonnade — Columns built in a row and joined together in order to provide a support for the area under them.
Clerestory — Uppermost level of a cathedral wall, whose purpose is to let in light or air.
Cornice — Decorative, horizontal ledge built at the roof line, projecting outward in order to divert rainwater.

Terms related to Ceilings, Domes, Spires or Towers.

Boss — a projecting stone at the intersection of ribs, frequently elaborately carved. Its function is to provide a net intersection of the ribs and tie them into one unit.
Vault — Arched shape structure intended to provide support for a raised ceiling.
Ribbed Vaulting — System of ceiling supports where the arches intersect each other in a regular pattern.
Crossing Tower — Tower built over the crossing between the Trancepts, Nave, and Choir of a church.
Belfry — Structure containing a bell, usually within a tower or steeple above a church
Domed Roof — Self-supporting circular arched roof built without external buttresses.
Pinnacles — Turrent tapering upward built on top of a buttress or supporting wall for either ornamental or structural purposes.
Spire — Tapered, pointed structure on the top of a building, or tower.
Campanile — Bell tower, especially one which is free-standing, detached from a church.
Lantern tower — Small windowed structure built atop a church roof over the central crossing area, in order to let in light.

Lancet window — Tall, narrow window with a pointed arch, frequently built in groups.
Rose Window — Circular stain-glass window, with mullions and treacery radiating from the center, commonly seen over main entrances of Cathedrals.
Stain glass window — Colored glass crafted such that small pieces of glass are arranged to form patterns or pictures, held together by strips of lead.
Tracery — Stonework that support the glass in a Gothic window. Also used to create geometric systems on wall panels and doors.
Trefoil — A carved three-leaved ornament, or a three lobed opening in tracery.
Quatrefoil — A figure used in window tracery, shaped to form a cross or four equal segments of a circle.
Mullion — Vertical, decorative stonework that forms a division between panes or panels of a window, door, or screen.
Oculus — Circular opening in the center of domed ceiling or a windowed wall.
Portal — Main door area or grand entrance of a church, gate, or fortified building.

Facade — Visual exterior of the front of a church usually including the entrance doors and surrounding windows.
Gargoyle — Stone carving of a grotesque creature with its mouth open, used to drain water from the roof, commonly associated with Gothic cathedrals
Niche — Recessed area in the face of a wall or pier, prepared to support a statue or decrative ornament.
Triptych — a picture, design or carving on three panels, often an altar piece.

Pews — Benches installed in Nave to provide permanent seating to congregation. Not common in churches until 17th century
Altar Rail — Low Barrier separating congregation from clergy, designed for communicants to kneel at when receiving communion.
Rood — Cross or crucifix that is hung in front of the altar or in front of the choir of a church.
Rood screen — Ornate partition between the Nave and the Choir area of a Cathedral.
Font — Basin of blessed water, usually on a pedestal, often kept near the entrance of a church for the purpose of baptism.
Lectern — Slanted desk or stand on which a Lectionary is placed, from which scriptures are chanted or read.
Sedilla — Chairs in the sanctuary, near the altar, where priests or deacons sit during portions of the mass they are not actively celebrating
Altar Stone — Stone containing relics of a saint inset into a cavity, used as part of a Catholic altar.
Reliquary — Container for relics, such as bones, pieces of cloth or some object associated with a saint.
Cathedra — Seat or throne of a bishop, and a symbol of the bishop's authority.
Choir Stalls — Finely carved wooden seats, running parallel to the choir area, where the clergy sit, stand or kneel during services.