How to Study Architecture

by Charles H. Caffin

[O]ctastyle: See Portico.

Ogee (pr. O-jée): another term for the Cyma Reversa. See Cyma.

Ogival: term applied to the Pointed Arch, because it is composed of two contrasted curves. Owing to this arch being characteristic of the Gothic style, the French have proposed to call the latter Ogival.

Open Arcades: See Arcades.

Opisthodomos (Gk. “room behind”): same as Epinaos. See Naos.

Opus reticulatum (lit. “net work”): a veneering composed of equal square slabs, arranged so that their joints are diagonal and form a net-like mesh.

Opus Sectile (lit. “Cut-work”): a mosaic ornament, composed of glass or marble, cut into various shapes to form a pattern. The richest variety of it is known as Opus Alexandrinum.

Opus Spicatum: pavement composed of bricks laid in “herring-bone” fashion.

Opus tesselatum: a mosaic ornament composed of tesseræ or square blocks of glass or marble.

Order: specifically, in Classic architecture, the combination of Column and Entablature.