Lacunar \La*cu"nar\, n.; pl. E. {Lacunars}
(l[.a]*k[=u]"n[~e]rz), L. {Lacunaria}
(l[a^]k`[-u]*n[=a]"r[i^]*[.a]). [L.] (Arch.)
(a) The ceiling or under surface of any part, especially when
it consists of compartments, sunk or hollowed without
spaces or bands between the panels. --Gwilt
(b) One of the sunken panels in such a ceiling.
[1913 Webster]