The Collaborative International Dictionary of English v.0.48:

Isopathy \I*sop"a*thy\, n. [Iso- + Gr. ? suffering.] (Med.)
   (a) The system which undertakes to cure a disease by means of
       the virus of the same disease.
   (b) The theory of curing a diseased organ by eating the
       analogous organ of a healthy animal. --Mayne.
   (c) The doctrine that the power of therapeutics is equal to
       that of the causes of disease.
       [1913 Webster]