The Collaborative International Dictionary
Basisphenoidal
Basisphenoid \Ba`si*sphe"noid\, Basisphenoidal \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.
Wiktionary
basisphenoidal
a. (alternative form of basisphenoid English)