Source : Webster's Revised Unabridged Dictionary (1913)

Hemiopia \Hem`i*o"pi*a\, Hemiopsia \Hem`i*op"si*a\, n. [NL., fr.
   Gr. ? half + Gr. ? sight.] (Med.)
   A defect of vision in consequence of which a person sees but
   half of an object looked at.