Source : Webster's Revised Unabridged Dictionary (1913)

Thermotherapy \Ther`mo*ther"a*py\, n. [Thermo- + therapy.]
   (Med.)
   Treatment of disease by heat, esp. by hot air.

Source : WordNet®

thermotherapy
     n : the use of heat to treat a disease or disorder; heating pads
         or hot compresses or hot-water bottles are used to
         promote circulation in peripheral vascular disease or to
         relax tense muscles