Source : Webster's Revised Unabridged Dictionary (1913)

Basisphenoid \Ba`si*sphe"noid\, Basisphenoidal
\Ba`si*sphe*noid"al\, a. [Basi- + spheroid.] (Anat.)
   Of or pertaining to that part of the base of the cranium
   between the basioccipital and the presphenoid, which usually
   ossifies separately in the embryo or in the young, and
   becomes a part of the sphenoid in the adult.