The Collaborative International Dictionary of English v.0.48:

Idiopathic \Id`i*o*path"ic\, Idiopathical \Id`i*o*path"ic*al\,
   a. [Cf. F. idiopathique.] (Med.)
   Pertaining to idiopathy; characterizing a disease arising
   primarily, and not in consequence of some other disease or
   injury; -- opposed to symptomatic, sympathetic, and
   traumatic. -- Id`i*o*path"ic*al*ly, adv.
   [1913 Webster]