• albarium opus: A setting coat of pure lime, finished as white as possible, and not intended to receive color.
• Alexandrinum opus: The third division of the medieval mosaic art, from the time of Constantine to the thirteenth century.
• amygdalatum opus: A type of opus reticulatum.
• antiquum opus: Also see opus incertum.
• caementicium opus: See opus caementicium.
• incertum opus: See opus incertum.
• lateritum opus: Brickwork of the ancient Romans.
• listatum opus: See opus listatum.
• lithostrotum opus: In ancient Greece and Rome, any ornamental pavement, such as mosaic.
• marmoratum opus: In plastering, a finish coat made of calcined gypsum mixed with pulverized stone or, for the finest work, with pulverized marble; used by the ancient Romans.
• opus: Work, in the sense of labor or its results.
• opus albarium: Same as albarium opus.
• opus Alexandrinum: A mosaic of relatively large pieces of marble or stone, cut to shape and arranged in geometric patterns, usually a mosaic pavement consisting of geometrical figures in black and red tesserae on white ground.
• opus antiquum: Also see opus incertum.
• opus caementicium: Ancient Roman masonry construction using undressed stones laid in a mortar composed of sand, lime, and pozzolan; in some Roman provinces, pozzolan was not used in the mortar.
• opus graecanicum: Work done in the Greek manner; apparently a pavement, as of mosaic, or an inlay of marble, supposed to resemble in pattern or in workmanship the work done by the Greeks.
• opus graecanium: Work done in the Greek manner; apparently a pavement, as of mosaic, or an inlay of marble, supposed to resemble in pattern or in workmanship the work done by the Greeks.
• opus incertum: In ancient Rome, masonry formed of small rough stones set irregularly in mortar, sometimes traversed by beds of bricks or tiles.
• opus interrasile: Decoration produced either by cutting away the ground and leaving the pattern or by cutting out the pattern so that the openings from the design.
• opus isodomum: Also see isodomum.
• opus latericium: Masonry of tiles, or faced with tiles.
• opus lateritium: Masonry of tiles, or faced with tiles.
• opus listatum: Ancient Roman masonry formed by alternating courses of brick and small stone blocks.
• opus lithostratum: See mosaic.
• opus lithostrotum: Also see lithostrotum opus.
• opus marmoratum: See marmoratum opus.
• opus mixtum: A wall facing of alternate courses of brick and small blocks of tufa; used from the 4th to 6th century A.D. in Roman construction.
• opus musivum: A Roman mosaic decoration employing small cubes of colored glass or enameled work.
• opus pseudisodomum: In ancient Roman masonry, coursed ashlar having courses of unequal height.
• opus quadratum: Masonry of squared stones in regular ashlar courses.
• opus reticulatum: A decorative Roman wall facing, backed by a concrete core, formed of small pyramidal stones with their points embedded in the wall, their exposed square bases, set diagonally, forming a net-like pattern.
• opus scalpturatum: See scalpturatum.
• opus sectile: Decorative paving of geometric marble slabs.
• opus signinum: Plaster or stucco stated to have been made of fragments of pottery ground up with lime; sometimes, as in Pompeii, used for floor covering, which much resembles terrazzo Veneziano. The name appears to be derived from the town of Signia in Latium.
• opus spicatum: Masonry faced with stones or tile which are arranged in herringbone fashion or in a similar pattern, producing sharp points or angles. The adjective spicatus, signifying having spikes or ears as of wheat, etc., is applicable to other surfaces than those of a wall. Thus, testacea spicata is a pavement laid herringbone fashion.
• opus tectorium: A type of stucco used in ancient Rome; used to cover walls in three or four coats, the finishing coat being practically an artificial marble, usually polished to serve as a surface for paintings.
• opus tesselatum: See mosaic.
• opus tessellatum: A pavement with designs executed in pieces of different-colored tesserae, of larger size and more regular form than the pieces used in mosaic.
• opus testaceum: In ancient Roman masonry, a facing composed of fragments of broken tile.
• opus topiarium: See topiarium opus.
• opus vermiculatum: Also see vermiculated mosaic.
• polygonium opus: Same as polygonal masonry.
• reticulatum opus: Also see opus reticulatum.
• scalpturatum opus: A use of inlaid colored marble, first introduced into Italy between 147 and 103 B.C.
• sectile opus: A kind of pavement formed of slabs or tiles of glass or other material, the pieces having a uniform size (far larger than the tesserae of ordinary mosaic) and being either plain-colored or mottled and veined.
• signinum opus: A type of ancient Roman surfacing material consisting of tiles beaten into powder and mixed with mortar; especially used to coat the interior of aqueducts and as a floor surface to keep out moisture.
• spicatum opus: Ancient Roman masonry laid in a herringbone pattern.
• tectorium opus: Also see opus tectorium.
• tessellatum opus: See opus tessellatum.
• topiarium opus: A wall painting representing trees, shrubs, and trelliswork, as at Pompeii.
• vermiculatum opus: See vermiculated mosaic.

Also see Architecture index.