aedicule. In classical architecture, a niche covered by a pediment or entablature supported by a pair of columns.

architrave. In classical architecture, the lintel or beam that rests on the capitals of columns.

ark (Hebrew, aron ha-kodesh). The receptacle where the Torah scrolls are stored.

attic. In building, either a room at the top of a house, or, in classical and Renaissance architecture, a low story or wall above the main order of a façade, as in the top of a triumphal arch. 

baldachin. A freestanding canopy used to cover and visually emphasize a place, object, or person of extreme significance.

barrel vault. A continuous arched shape that may approximate a semi-cylinder form, resembling the roof of a tunnel.

belvedere. An architectural structure sited to take advantage of a scenic view.

bifora window. A type of window divided vertically in two openings by a small column or a pilaster; the openings are topped by arches, round or pointed. Sometimes the bifora is framed by a further arch.

bimah (Hebrew). The platform in the synagogue on which the Torah is placed for reading. The bimah usually is placed on the main (east-west) axis, in the center of the synagogue in Ashkenazic Orthodox synagogues, at the east end in Ashkenazic Reform synagogues, and opposite the ark in Sephardic-, Italian- synagogues.

bull’s-eye (oeil-de-boeuf) window. A small circular or oval window, usually resembling a wheel, often with glazing bars (bars framing the panes of glass) as spokes radiating outward from an empty hub, or circular center.

clerestory. Any fenestrated (windowed) wall of a room that is carried higher than the surrounding roofs to light the interior space.

corbel table. A continuous row of corbels (blocks of stone projecting from a wall and supporting some heavy feature), usually placed just below the eaves to fill in beneath a high-pitched roof and to give extra support. It was a popular architectural feature in Romanesque buildings, often in the form of rows of continuous small arches.

cupola. A small dome resembling an overturned cup, placed on a circular, polygonal, or square base or on small pillars or a glassed-in lantern. It is used to crown a turret, roof, or larger dome. The inner vault of a dome is also a cupola.

drum. The circular or polygonal wall supporting a dome, cupola, or lantern.

Dunleith red sandstone. A type of stone from Iowa used for building, and especially architectural details.

entablature. An assemblage of horizontal moldings and bands supported by and located immediately above the columns of classical buildings, or similar structural supports in non-classical buildings.

fenestration. The arrangement of a building’s doors and windows (from the Latin word for window: fenestra).

finial. The decorative top of a pinnacle, gable end, buttress, canopy, or spire.

frieze. In classical architecture, the middle of the three main divisions of an entablature (section resting on the capital). The frieze is above the architrave and below the cornice, in a position that could be quite difficult to view. The term also refers to any long, narrow, horizontal panel or band used for decorative purposes—e.g., on pottery, on the walls of a room, or on the exterior walls of buildings.

gable. The triangular section of wall at the end of a pitched roof, extending from the eaves to the peak. The gables in classical Greek temples are called pediments.

hip roof or hipped roof. A roof that slopes upward from all sides of a structure, having no vertical ends.

keystone (capstone). The central stone at the peak of an arch.

lancet window. A tall narrow window with a pointed arch at its top. It acquired the “lancet” name from its resemblance to a lance. This type of window is frequently found in medieval architecture, especially in churches and towers.

lantern. The open top story of a dome or tower, so named because it resembled a lamp container.

narthex. A porch or vestibule of a church, preceding the nave.

oculus window. A window that is circular or oval in shape, such as an oeil-de-boeuf window. The round opening at the top of some domes, or cupolas, is also an oculus, as in the Pantheon in Rome.

quoin. Both the external angle or corner of a building and, more often, one of the stones used to form that angle. These cornerstones are both decorative and structural, since they usually differ in jointing, color, texture, or size from the masonry of the adjoining walls.

Palladian window. A three-part window composed of a large, arched central section flanked by two narrower, shorter sections having square tops.

pediment. A triangular gable forming the end of the roof slope over a portico (the area, with a roof supported by columns, leading to the entrance of a building); or a similar form used decoratively over a doorway or window. 

pilaster. A shallow rectangular column that projects slightly beyond the wall into which it is built.

polychromy. The practice of decorating architectural elements, sculpture, etc., in a variety of colors.

portico. A colonnaded porch leading to a building’s entrance, or a covered walkway that is enclosed by walls and supported by regularly-spaced columns.

roundel. A small circular decorative plate or panel used extensively in Renaissance courtyards and arcades. A roundel window is a small, ornate, circular window. 

rustication. An intentional decorative treatment of masonry to give the appearance of rough or rustic construction, often achieved by cutting back the edges of stones to a plane surface while leaving the central portion of the face either rough or projecting markedly.

St. Louis limestone. A layer of limestone found in Indiana used for building and (after crushing) for cement and cast-blocks.

vegetal. A decorative style featuring plant motifs, such as vines, branches, leaves, flowers, and fruits, especially for borders and backgrounds. It was employed in different periods, including antiquity and the Renaissance, but also in the late 19th and early 20th centuries in the Art Nouveau and Arts and Crafts Movements.

voussoir. A wedge-shaped element, typically a stone, used in building an arch or vault. The central voussoir of an arch is known as a keystone.