Oculus (architecture)
circular opening in the center of a dome or in a wall
An oculus (from Latin oculus 'eye'; pl. oculi) is a circular opening in the center of a dome or in a wall. Originating in classical architecture, it is a feature of Byzantine and Neoclassical architecture.
A horizontal oculus in the center of a dome is also called opaion (from Ancient Greek ὀπαῖον (opaîon) '(smoke) hole'; pl. opaia).
Oeil-de-boeuf
An oeil-de-boeuf (French: [œj.də.bœf]; English: "bull's eye"), also œil de bœuf and sometimes anglicized as ox-eye window, is a relatively small elliptical window, typically for an upper storey, and sometimes set in a roof slope as a dormer, or above a door to let in natural light. These are relatively small windows, traditionally oval. The term is increasingly used for circular windows (in which case it could also be called an oculus), but not for holes in domes or ceilings.
Windows of this type are commonly found in the grand architecture of Baroque France. The term is also applied to similar round windows, such as those found in Georgian architecture in Great Britain, and later Greek Revival and Colonial Revival styles in North America, so that must be considered part of the usage. The term initially applied to horizontal elliptical windows, but is also used for vertical ones.
The spread is not limited to ecclesiastical architecture.
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This entry incorporates text from “Oculus (architecture)” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.