Source : Webster's Revised Unabridged Dictionary (1913)

Postaxial \Post*ax"i*al\, a. [Pref. post- + axial.] (Anat.)
   Situated behind any transverse axis in the body of an animal;
   caudal; posterior; especially, behind, or on the caudal or
   posterior (that is, ulnar or fibular) side of, the axis of a
   vertebrate limb.