Architecture Glossary
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Octastyle – Of a portico with eight frontal columns.
St. George - Liverpool
Odeon, odeion, or odium – In ancient Greek and Roman architecture a small roofed theatre, for concert and lectures.
Odeum of Herodes Atticus
Œil-de-bœuf window – A small round or, more usually, oval window as in the Salon de l’Œil de Bœuf at Versailles. There are three ranges of them in the dome of St Peter’s, Rome.
Œillet – In medieval architecture, a small opening in fortification through which missiles could be discharged.
Ogive – The French name for a pointed arch, hence ogival, a term applied to French Gothic architecture, but no longer used.
Onion dome – A pointed bulbous dome common in Russia and Eastern Europe, especially on churches and church towers. Structurally it is not a true dome, i.e. it is not vaulted.
Cathedral of the Savior inside the Kremlin
Section through the Temple of the Goddess Athena Aphaea
1: Inner Walls. 2: The roof. 3: Inner Columns. 4: Opistodomos or rear porch.
5: View of the Cella. 6: Cult Statue of the Goddess Athena Aphaea
7: The Pool of Olive Oil. 8: Ramp from Altar to Temple. 9: Corner Columns.
10: Metope. 11: Triglyph. 12: The East Pediment Sculptures.
Opisthodomos – The enclosed section at the rear of a Greek temple, sometimes used as a treasury.
Optical refinements – Subtle modifications to profiles or surfaces to correct the illusion of sagging or disproportion in a building. See entasis.
Opus Alexandrinum – Ornamental paving combining mosaic and opus sectile in guilloche design.
Opus incertum – Roman walling of concrete faced with irregularly shaped stones.
Opus listatum – Walling with alternating course of brick and small blocks of stone.
Opus quadratum – Roman walling of squared stones.
Opus reticulatum – Roman walling of concrete faced with squared stones arranged diagonally like the meshes of a net.
Opus sectile – Ornamental paving or wall covering made from marble slabs cut in various, generally geometric, shapes.
Oratory – A small private chapel, either in a church or in a house; or a church of the Oratorian order of S. Filippo Neri, e.g. the Brompton Oratory, London.
San Filippo Neri
Orchaestra or orchestra – The circular ‘dancing floor’ of an ancient Greek theatre, whence the corresponding semicircular space in front of the stage or proscenium of an ancient Roman theatre.
Order – In classical architecture, a column with base, shaft, capital, and entablature, decorated and proportioned according to one of the accepted modes – Doric, Tuscan, Ionic, Corinthian, or Composite.
Ordonnance – The disposition of the parts of a building. In French the term was used by c 17-c 18 theorist in allusion to the choice of an appropriate order for a building and to its application.
Oriel window - An oriel window projects from the wall and does not extend to the ground. Oriel windows originated as a form of porch. They are often supported by brackets or corbels.
Orthostat – A slab of stone set upright at the base of a wall or building to form the lower section of it, sometimes carved in relief.
Overhang – Projection of the upper storey of a house.
Oversailing courses – A series of a stone or brick courses, each one projecting beyond the one below it.
Ovolo moulding – A convex moulding, usually a quarter of a circle and sometimes called a quarter round. It is often ornamented with egg and dart or other similar patterns.
Architecture Glossary
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