Webster’s Revised Unabridged Dictionary · 1913
Basisphenoid
Ba′si·sphe′noid, Ba′si·sphe·noid′al, a. [Basi- + sphenoid.] (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.
Ba′si·sphe′noid, n. (Anat.) The basisphenoid bone.