Source : Webster's Revised Unabridged Dictionary (1913)

Atony \At"o*ny\, n. [Gr. ? slackness; 'a priv. + ? tone,
   strength, ? to stretch: cf. F. atonie.] (Med.)
   Want of tone; weakness of the system, or of any organ,
   especially of such as are contractile.

Source : WordNet®

atony
     n : lack of normal muscular tension or tonus [syn: {atonicity},
         {atonia}, {amyotonia}] [ant: {tonicity}]