lacunar

from The Collaborative International Dictionary of English v.0.48

Lacunal \La*cu"nal\ (l[.a]*k[=u]"nal), Lacunar \La*cu"nar\
   (l[.a]*k[=u]"n[~e]r), a.
   Pertaining to, or having, lacun[ae]; as, a lacunar
   circulation.
   [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

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]