lacunar

adj. of or pertaining to a lacuna; incomplete, having gaps or missing parts; pitted, having cavities (Anatomy)

n. (Architecture) sunken panel; ceiling or arch decorated with sunken panels

sweetFor other architecture terminology, refer to:: List of classical architecture termsClassical orderDecorative molding
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adj. lacunar, of or pertaining to a lacuna; incomplete, having gaps or missing parts; pitted, having cavities (Anatomy)

(n.)
The ceiling or under surface of any part, especially when it consists of compartments, sunk or hollowed without spaces or bands between the panels.
  

(n.)
One of the sunken panels in such a ceiling.
  

(a.)
Pertaining to, or having, lacunae; as, a lacunar circulation.
  

a candle beam.