a. [ Sphenoid + ethmoid. ] (Anat.) Of or pertaining to both the sphenoidal and the ethmoidal regions of the skull, or the sphenethmoid bone; sphenethmoidal. [ 1913 Webster ]

Sphenethmoid bone (Anat.), a bone of the skull which surrounds the anterior end of the brain in many amphibia; the girdle bone. [ 1913 Webster ]

n. (Anat.) The sphenethmoid bone. [ 1913 Webster ]

a. (Anat.) Relating to the sphenoethmoid bone; sphenoethmoid. [ 1913 Webster ]