\Sphe*neth"moid\, a. [Sphenoid + ethmoid.] (Anat.)
Of or pertaining to both the sphenoidal and the ethmoidal
regions of the skull, or the sphenethmoid bone;
sphenethmoidal.

{Sphenethmoid bone} (Anat.), a bone of the skull which
   surrounds the anterior end of the brain in many amphibia;
   the girdle bone.

\Sphe*neth"moid\, n. (Anat.)
The sphenethmoid bone.