\Sphe"noid\, a. [Gr. ???; sfh`n a wedge + e'i^dos form:
cf. F. sph['e]no["i]de.]
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}.

\Sphe"noid\, 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.