Sphenoid

a.	1.	Wedge-shaped; as, a sphenoid crystal.
	2.	(Anat.) Of or pertaining to the sphenoid bone. Sphenoid bone (Anat.) an irregularly shaped bone in front of the occipital in the base of the skull of the higher vertebrates. It is composed of several fetal bones which become united the adult. See Alisphenoid, Basisphenoid, Orbitosphenoid, Presphenoid.
n.	1.	(Crystallog.) A wedge-shaped crystal bounded by four equal isosceles triangles. It is the hemihedral form of a square pyramid.
	2.	(Anat.) The sphenoid bone.

Noun

1.

sphenoid - butterfly-shaped bone at the base of the skull Synonyms: os sphenoidale, sphenoid bone

bone, crotaphion, os, os sphenoidale, pterygoid process, skull, sphenoid bone