The Collaborative International Dictionary of English v.0.48:

Sthenic \Sthen"ic\, a. [Gr. ? strength: cf. F. sth['e]nique.]
   (Med.)
   Strong; active; -- said especially of morbid states attended
   with excessive action of the heart and blood vessels, and
   characterized by strength and activity of the muscular and
   nervous system; as, a sthenic fever.
   [1913 Webster]

   Sthenic theory. See Stimulism
   (a) .
       [1913 Webster]