SAH Archipedia uses terms from the Getty Art and Architecture Thesaurus (AAT) to categorize and classify metadata for the entries in the database. For more information on the Getty AAT, click here

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oak (wood)

Wood of trees belonging to the genus Quercus, of the beech family. It is a durable wood that has a distinctive coarse grain, used in cabinetry, flooring, paneling, musical instruments, ship interiors and moldings, panel painting, and sculptures.


Loosely twisted hemp or jute fiber impregnated with tar or a tar derivative and used in caulking seams, as of wooden ships, and packing joints, as of pipes.

oil paint (paint)

A paint made by grinding pigments with a drying oil such as linseed oil. After 1940 alkyd binders were often added to oil paint to provide faster drying times.


Textile waterproofed with oil; often woven cotton, jute, or hemp, treated with oil and pigment. Typically used as a waterproof covering.

Olea europaea (species)

Species of small evergreen tree native to coastal areas of the eastern Mediterranean Basin, western Asia, northern Africa, and the northern Middle East. It has long been cultivated for its drupaceous fruit that is an important food and source of oil. The wood is resistant to decay; if the top dies back, a new trunk will often arise from the roots. The species may have arisen in northern tropical Africa, then spread to the Mediterranean Basin. It had been cultivated on Crete since 3,500 BCE; fossilized leaves of the genus date to 37,000 years before present. Sometimes divided into several subspecies.

onyx (mineral)

A variety of chacedony having parallel, alternating bands of chalcedony and opal. The bands are usually colored black and white or reddish and white. In ancient times, the stones were available in Egypt, Arabia, and India. Onyx was often used as a gemstone in the production of cameos and intaglios. Onyx is also used as an ornamental building stone and for decorative items such as table tops, lamp bases, and small boxes.

onyx glass

Term used in the glass trade for a glass made to resemble onyx either by the addition of metal and metallic oxide that impart a silver luster upon heating, or by mixing glass of contrasting colors.

onyx marble

A compact variety of calcite that has dark layers of impurities and polishes to a high gloss, resembling onyx in appearance. It is typically used as a decorative or architectural material or for small ornamental objects.

oolitic limestone

Limestone containing many small, rounded particles, which are concentric layers of calcium carbonate deposits.

open-timbered roofs

Roofs in which the wooden structure is exposed to the rooms below.

organic material

Material containing carbon, including those derived from living organisms.

oriel windows

Bay windows projecting from an upper floor and not extending to the ground; usually supported by brackets or corbels.

oriented strand board

Layered composite wood board consisting of cross-oriented thin, rectangular strips compressed and glued together with resin adhesives.

oyster shell

Shell of an oyster.