Source : Webster's Revised Unabridged Dictionary (1913)

Asthenia \As`the*ni"a\, Astheny \As"the*ny\, n. [NL. asthenia,
   Gr. 'asqe`nia; 'a priv. + sqe`nos strength.] (Med.)
   Want or loss of strength; debility; diminution of the vital
   forces.

Source : WordNet®

astheny
     n : an abnormal loss of strength [syn: {asthenia}]