Source : Webster's Revised Unabridged Dictionary (1913)

Sphenethmoid \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.