The Collaborative International Dictionary of English v.0.48:
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. [1913 Webster]WordNet (r) 3.0 (2006):
asthenia n 1: an abnormal loss of strength [syn: asthenia, astheny]