myosis

from WordNet (r) 3.0 (2006)

myosis
    n 1: an acute infectious disease occurring in epidemic form and
         featuring paroxysms of pain (usually in the chest) [syn:
         {epidemic pleurodynia}, {epidemic myalgia}, {myosis},
         {diaphragmatic pleurisy}, {Bornholm disease}]
    2: reflex contraction of the sphincter muscle of the iris in
       response to a bright light (or certain drugs) causing the
       pupil to become smaller [syn: {light reflex}, {pupillary
       reflex}, {miosis}, {myosis}]

from The Collaborative International Dictionary of English v.0.48

Myosis \My*o"sis\, n. [NL., fr. Gr. ? to close the eyes or
   lips.] (Med.)
   Long-continued contraction of the pupil of the eye.
   [1913 Webster]