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

Click on the icon to view the definition of the selected term.

natural ventilation (systems)

Ventilation systems that depend on natural atmospheric conditions and the manual operation of building openings, such as windows, doors, and transoms.

Naugahyde (TM)

Brand of strong vinyl-coated cloth made to look like leather.

nautilus shell

The shell of the pearly nautilus, Nautilus macromphalus, native to the tropical Pacific and Indian Oceans, used to make decorative objects such as cups, salts, and jewelry, and as carving material.


Inert gaseous element with symbol Ne and atomic number 10; used as the medium in some electric discharge lamps.

neon lamps

Lamps consisting of exhausted glass tubes filled with neon gas that is ionized and conducts an electric current through the tube.


Synthetic rubber made by polymerization of chloroprene and characterized by superior resistance to oil, gasoline, sunlight, ozone, and heat, and by lower permeability to gas than rubber.


Inexpensive, low quality paper made from wood pulp, of the type used chiefly for printing newspapers.

nickel (metal)

Pure metallic element having symbol Ni and atomic number 28; a silvery white metal with a yellowish cast, resistant to corrosion and to most acids except nitric. Use also for this metal as processed and formed, usually in combination with other substances, to make various objects and materials.

nickel silver

Alloy of copper, nickel, and zinc, the nickel serving to enhance color. Uses include operations that require ductility in the cold state, such as stamping, spinning, deep drawing, and for articles to be plated.


Masonry, usually brickwork or stone, used as nonstructural fill in the spaces between major wood wall members in timber construction.

Norway pine (wood)

Wood from the Pinus resinosa, found in North America.

Norway spruce (wood)

Wood of the Picea abies, native to northern Europe and used as a timber and ornamental tree.

Numidian marble

The color of this marble ranges from yellow, light brown, and pink to deep red. It originates not from Numidia proper, but from the mountains of Algeria and Mauritania.


Any of a variety of thermoplastic polymers originally developed as textile fibers and used in fabrics. They have a straight-chain polyamide structure and are largely heat-resistant.

Nyssa sylvatica (species)

Species of tree found in moist areas of the eastern U.S. from Maine south to the Gulf Coast and westward to Oklahoma. Its wood is light and soft, but tough. The black gum is sometimes grown as an ornamental, prized for brilliant scarlet autumnal foliage. The bark dye has good washfastness and fair lightfastness.

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.

paint (coating)

Any dispersion of pigment in a liquid binder. Paint is applied with a brush, roller, sprayer, or by dipping and dries to form a decorative or protective film.

paintings (visual works)

Unique works in which images are formed primarily by the direct application of pigments suspended in oil, water, egg yolk, molten wax, or other liquid, arranged in masses of color, onto a generally two-dimensional surface.

palisades (outworks)

Barriers composed of long stakes, usually with pointed tops, driven into the earth close together, sometimes connected by horizontal beams.

pampas grass (material)

Material comprising the stem and leaves of the grass species Cortaderia selloana, used for making ropes and baskets.

panel (wood by form)

Wood in the form of broad, thin, flat or sometimes curved pieces that serve as a support for media in visual works; examples are paintings on wood. In architecture and other constructive arts, use "panels (surface components" to refer to a panel, whether of wood or another material, that is typically a compartment of a surface either sunken below or raised above the general level, and set in a molding or other border, as in a frame, sometimes of different color or material.

panel painting (image-making)

Refers to the activity of painting portable paintings on wood from the painting of other types, such as mural paintings and manuscript illuminations, especially with reference to the Medieval and Early Renaissance periods.


Wall coverings consisting of panels of wood or other material joined in a continuous surface.

panels (surface components)

Distinct portions, sections, or divisions of a surface, especially when sunk below or raised above the general level or enclosed by a frame or border. Common on walls, ceilings, and doors, and also on furniture pieces.


In ancient architecture, a term used to describe a flat tile or tegula. In modern usage, an S-curved roofing tile, laid so the down curve of one tile overlaps the up curve of the next one.

papier mâché

Composite material used for molding objects; made of repulped or pulverized paper and a liquid adhesive binder. May also comprise strips of paper, sometimes reinforced with textiles, stuck together with a wet adhesive, and used to form an object. The object becomes solid when the paste dries; the object may then be sanded, lacquered, and painted. Such objects are very durable; they first developed in Asia and were common in Europe and elsewhere since the 17th century.

papyrus (fiber product)

A writing material prepared from thin strips of the pith of the papyrus plant laid together, soaked, pressed, and dried.

paragon (marble)

Black marble quarried in Greece and Egypt, used as a touchstone and from the late 16th century in Verona used for painting on.


Low walls, projecting from the edge of platforms, terraces, or roofs, or surmounting the cornices of a building; also, walls forming the uppermost part of defensive walls or ramparts.


Marquetry executed in a geometrical pattern, used especially for floors.

particle board

A composite wood board made from small wood chips mixed with a water-insoluble adhesive, then compressed into a dense solid panel. Particle boards were originally made in 1915 as wallboards. The most common adhesive in particle boards is urea formaldehyde glues are used which release volatile formaldehyde. Some particles boards are made with polyurea or phenolic resins. Particle boards are water-resistant, insect resistant, and dimensionally stable during humidity and temperature fluctuations. Particle boards are commonly used in the construction of inexpensive furniture, cabinetry and mobile homes.

paste (glass)

A brilliant glass of high lead content used for the manufacture of artificial gems; also an imitation gem made of this material.

paver (material)

Any brick, tile, stone, or other material fabricated in shaped units and used for paving.

paving asphalt

Natural or modified asphalt or an asphalt aggregate intended for use as a binder in asphalt concrete.

paving brick

A vitrified brick, especially suitable for use in pavements where resistance to abrasion is important.

paving stone

A block or chunk of stone that is shaped or selected by shape for a paved surface.

paving tile

Tile designed to be used for areas of pavement.


A white or drab yellow marble with purplish veins, it was supposedly favored by the emperor Hadrian. The word pavonazzo means peacock blue, violet, or purple in Italian. The ancient marble is also known as Phrygian marble because it is believed to have come from Phrygia in Asia Minor.

pea gravel

Small-diameter (6.4 to 9.5 mm or 1/4 to 3/8 in.) natural gravel, screened to specification.

pearl (animal material)

A smooth round bead formed primarily within the shells of two distantly related groups of molluscan bivalves or clams, including the ocean-dwelling pearl oysters and the freshwater river mussels. Pearls are used in jewelry and for other ornamental puposes; they are considered a gem.

pebble (rock)

A rock fragment, generally rounded by abrasion, larger than a granule and smaller than a cobble; it has a diameter in the range of 4 to 66 mm, or a size between that of a pea and that of a tennis ball.

pebble dash

Textured surfaces made from mortar with small stones embedded in it, used as a coating for walls or floors.

pecan (wood)

Wood of the species Carya illioensis, native to the southeastern United States and Mexico having reddish brown heartwood with dark brown stripes. It is used for interior millwork, handles, and other items.


Plants which remain green and leafy throughout the year, usually with new herbaceous growth from perennating parts.

perforated brick

Brick with vertical perforations or holes; the addition of holes decreases the weight of the brick without significantly reducing its strength.

permanent white

An unstandardized name for certain white pigments, referring often to blanc fixe, zinc white, or mixtures of barium sulfate with zinc white.

pewter (tin alloy)

Alloy of tin and various proportions and combinations of lead and antimony, and sometimes also copper.

photovoltaic cells

Devices in which electromagnetic radiation is generated by a potential at a junction between two types of material, upon absorption of radiant energy.

Picea (genus)

Genus of around 35 species of coniferous evergreen trees in the family Pinaceae, order Pinales, found in northern temperate and boreal. Mature trees may be 20-60 m (66-200 feet) tall. They are distinguished from similar genera by whorled branches, conical form, with needle-like leaves attached singly to the branches in a spiral fashion, and rough rather than smooth branches. As needles are shed throughout the life of the tree, the branches retain a rough appearance from the pulvinus, to which the needles had been attached. Comprises around 40 species of evergreen ornamental and timber trees native to the temperate and cold regions of the Northern Hemisphere. They are pyramidal trees with whorled branches and thin, scaly bark.

Picea sitchenis (species)
No description is available for this term.

pierced walls

Masonry walls in which material has been removed without jeopardizing structural integrity, either for decorative or structural reasons. Masonry walls in which material has been removed without jeopardizing structural integrity, either for decorative or structural reasons.


Any relatively insoluble organic, inorganic, natural or artificial substance that imparts a color to another substance or mixture and always appears as the same specific color when viewed in white light. It is the constituent of paint or ink that provides the color. Distinguished from a dye, which is soluble in the vehicle, a pigment is insoluble in the vehicle, but instead is held in a suspension.

pilaster brick

A brick for constructing pilasters or slightly projecting piers, the end of which is so notched or rebated that it bonds more readily with the backing, thus increasing the stiffening of the wall.

piles (structural elements)

Timber, steel, or precast concrete columns serving as subsurface supports for vertical loads; distinct from "piers (foundation components)" which are larger and are never clustered.

pin oak (wood)

Wood from the species Quercus palustris, native primarily to bottomlands and moist uplands of eastern North America, but found as far west as Oklahoma and Ontario, Canada. It is a reddish brown hard wood that shrinks and cracks with drying; sometimes sold as red oak for flooring and lumber, but it is weaker and contains more knots.

pine (wood)

Wood from numerous trees of the genus Pinus. Pine is used largely in the construction and paper industries, although it is also a source of turpentine, resins, and oils, among other products.

pine tar

Wood tar produced by distilling pine wood, used in wood preservatives and medicinal products.

pink granite

Granite with a mineral composition that results in a pink color.

pink marble

Marble with a mineral composition resulting in a predominantly pink color.

Pinus (genus)

Genus containing about 90 species of ornamental and timber evergreen conifers in the family Pinaceae.

Pinus ponderosa (species)

Species of widespread and variable pine native to western North America and widely cultivated elsewhere for its timber and for ornament.

pipe clay

A type of fine white clay used to make tobacco pipes and fine earthenwares.


A building material consisting of stiff earth or clay forced in between forms.

plain sawed lumber

Wood cut at a tangent to the annual growth rings.

plank (wood)

Wood in the form of long, wide, square-sawn, smooth, flat pieces. A plank is typically characterized by being a length of timber sawn for building or other purposes to a thickness of from two to six inches, a width of nine inches or more, and eight feet or upwards in length.

plant material
No description is available for this term.

planters (containers)

Any of various containers in which plants are grown or placed for decorative purposes.


Refers to a soft, plastic material that can be spread or daubed on a wall, ceiling, or other surface, where it afterwards hardens. In the context of art and architecture, it generally refers specifically to a mixture of water, lime, and sand, often combined with other materials, such as animal hair, to give the resulting material strength, texture, and if the surface is to be painted, porosity.

plaster of Paris

Calcium sulfate hemihydrate, a white powder, which sets rapidly upon the addition of water; used for molds, sculpture, casts.

plasterwork (visual works)

Visual works made of plaster, which is a soft, plastic material, in this context usually a mixture of water, lime, and sand, often combined with other materials, such as animal hair. Plasterworks are either applied smoothly to a surface or as a combination of high-relief, sculptural, and surface decoration.

plastic (organic material)

A general term for any of a large and varied class of natural or synthetic organic materials that can be molded, extruded, or cast when soft or liquid, and then set into a rigid or slightly elastic form. Natural plastics include tree resins, beeswax, gutta-percha, horn, and clay. Synthetic plastics were first made in the 19th century. Plastics are used widely in manufacturing.

plastic laminate

Resin-impregnated materials, such as paper or fabric, produced under heat and high pressure to form an insoluble homogeneous piece. Laminates were first made in 1907 by Leo Baekeland when he coated canvas with phenol formaldehyde. Distinguished from "laminated plastic" which is a thin sheet of superimposed layers of plastic bonded or impregnated with resin and compressed under heat.

Platanus acerifolia (species)

Species that is a hybrid of Platanus occidentalis and Platanus orientalis. It combines characteristics of both in varying degrees. It is a little shorter and more squat than the American (occidentalis) tree and usually has bristly, paired seedballs. There are variegated forms of London plane. It is planted widely in cities for its resistance to air pollution and to diseases that more readily affect other plane trees.

Platanus occidentalis (species)

Species of plane tree native to North America; the tallest of the plane trees, reaching more than 50 m (160 feet) in height. Its pendent, smooth, ball-shaped seed clusters usually dangle singly and often persist after leaf fall. It is distinguished from other trees by its mottled exfoliating bark, which flakes off in great irregular masses, leaving the surface mottled, and greenish-white, gray and brown. For trees known simply as "sycamore," use Acer Pseudoplatanus, which is a species of maple.

plate glass

Any glass that has been rolled or cast into a sheet and then ground and polished.

platform frames

Wood structural frames in which the studs are only one story high, the floor joist of each story rests on the top plates of the story below or on the foundation sill for the first story, and the bearing walls and partitions rest on the subfloor of each story.

platinum (metal)

Pure metallic element having symbol Pt and atomic number 78; a lustrous, malleable, ductile, silvery white metal, considered a precious metal. Use also for this metal as processed and formed, usually in combination with other substances, to make objects and materials.

Plexiglas (TM)

Proprietary name for polymerized methyl methacrylate, used as a substitute for glass in products such as windows, skylights, illuminated signs, and aircraft. Plexiglas was trademarked by Rohm and Haas AG in Germany ca. 1930s.

plinth brick

A brick beveled on its face or end to provide for the reduction in thickness between the plinth and the main part of a wall.

plug tobacco

Chewing tobacco produced in the form of a flat cake.

plum (fruit)

Drupe, or stone-fruit, from several trees of the genus Prunus. The plum usually has red, purple, or yellow skin, and when ripe, a powdery bloom.


Wood board consisting of a number of thin layers of rotary-cut veneers glued together so that the grain of each layer is at right angles to the grain of the adjacent layer.


Thermoplastic polyester used in glazing, including bullet- and explosion-resistant laminates.

polyester (resin)

Resin formed by the reaction between dibasic acid and dihydroxy alcohol.


A group of polyolefin polymers derived from ethylene by polymerization by heat and pressure.

polygonal masonry

Building material comprising uncoursed masonry used in the ancient Mediterranean world. Laid up of large blocks of stone in rough polygonal shapes, often fitted together without mortar. Similar to "cyclopean masonry," but with more precise fitting of stones due to the straight hewn sides.


A clear plastic or stiff foam, a polymer of styrene, used chiefly as an insulator in refrigerators, air conditioners, and for packaging.