Source : Webster's Revised Unabridged Dictionary (1913)

Zygapophysis \Zyg`a*poph"y*sis\, n.; pl. {Zygapophyses}. [Gr. ?
   a yoke + E. apophysis.] (Anat.)
   One of the articular processes of a vertebra, of which there
   are usually four, two anterior and two posterior. See under
   {Vertebra}. -- {Zyg`ap*o*phys"i*al}, a.