The Collaborative International Dictionary of English v.0.48:

Occipital \Oc*cip"i*tal\, a. [Cf. F. occipital.] (Anat.)
   Of or pertaining to the occiput, or back part of the head, or
   to the occipital bone.
   [1913 Webster]

   Occipital bone (Anat.), the bone which forms the posterior
      segment of the skull and surrounds the great foramen by
      which the spinal cord leaves the cranium. In the higher
      vertebrates it is usually composed of four bones, which
      become consolidated in the adult.

   Occipital point (Anat.), the point of the occiput in the
      mesial plane farthest from the ophryon.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Occipital \Oc*cip"i*tal\, n. (Anat.)
   The occipital bone.
   [1913 Webster]

WordNet (r) 3.0 (2006):

occipital
    adj 1: of or relating to the occiput; "occipital bone"