OrbitosphenoidOr`bi*to*sphe"noid\, a. [Orbit + sphenoid.] (Anat.) Of or pertaining to the sphenoid bone and the orbit, or to the orbitosphenoid bone. -- n. The orbitosphenoid bone, which is situated in the orbit on either side of the presphenoid. It generally forms a part of the sphenoid in the adult.