Webster’s Revised Unabridged Dictionary · 1913
Œil-de-bœuf
Œil′-de-bœuf′, n.; pl. Œils-de-bœuf (#). [F., lit., eye of an ox.] (Arch.) A circular or oval window; — generally used of architecture of the 17th and 18th centuries. A famous room in the palace of Versailles bears this name, from the oval window opening into it.