The Collaborative International Dictionary of English v.0.48:

Hypostrophe \Hy*pos"tro*phe\, n. [NL., fr. Gr. ?, fr. ? to turn
   round or back; ? under + ? to turn.] (Med.)
   (a) The act of a patient turning himself.
   (b) A relapse, or return of a disease.
       [1913 Webster]