Source : Webster's Revised Unabridged Dictionary (1913)

Isocephalism \I`so*ceph"a*lism\, n. [From Gr. ? like-headed. See
   {Iso-}, and {Cephalon}.] (Art)
   A peculiarity in the design of bas-relief by which the heads
   of human figures are kept at the same height from the ground,
   whether the personages are seated, standing, or mounted on
   horseback; -- called also {isokephaleia}.