Illustrated Companion to the Latin Dictionary/Lacunar

This article incorporates text from a publication now in the public domain: Rich, Anthony (1849). The illustrated companion to the Latin dictionary, and Greek lexicon. p. vi. OCLC 894670115. https://archive.org/details/illustratedcompa00rich. 

LACU'NAR (φατνώμα). A coffer or panel in a flat ceiling, formed by the beams and rafters supporting the roof or flooring of an upper story, which cross each other at right angles, and, when they are left exposed, are seen to divide the whole soffit into a number of square compartments, like a pit or lake (lacuna, lacus), from which appearance the name arose. (Vitruv. vii. 2. 2. Cic. Tusc. v. 21. Hor. Od. ii. 18. 2.) The illustration (Lacunar/1.1) represents a flat ceiling of this description from the Vatican Virgil; but, as it was customary to imitate wood-work in brick and masonry, coffers of a similar description are often formed in arched or domed ceilings of which the Pantheon at Rome affords an example.

2. A particular kind of sun-dial (Vitruv. ix. 8.), which may be readily imagined from the name, although no specimen of it is known to exist; as a dial sunk in a slab, like the coffer in a ceiling.

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  Lacunar/1.1