The Collaborative International Dictionary of English v.0.48:

akinesia \ak`i*ne"si*a\ ([=a]`k[i^]*n[=e]"s[=e]*[.a] or
   [a^]k`[i^]*n[=e]"s[i^]*[.a]), n. [Gr. 'akinhsi`a quiescence;
   'a priv. + ki`nhsis motion.] (Med.)
   Loss of the ability for voluntary muscle movement. --Foster.
   [1913 Webster + AS] akinetic

WordNet (r) 3.0 (2006):

akinesia
    n 1: motionlessness attributable to a temporary paralysis [syn:
         akinesis, akinesia]