In cephalometrics and craniometrics, the most lateral point of the zygomatic arch. ... Origin: G. A later form of zygon, yoke ... (05 Mar 2000) ... 
(zij´e-on) the most lateral point on the zygomatic arch.
zygion (s), zygia (pl) A craniometric and cephalometric landmark, being the most laterally situated point on either zygomatic arch. The zygomatic arch is that part of the temporal bone of the skull that forms the prominence of the cheek.