idiopathic

From idio- +‎ -pathic. First appears c. 1669, in the publications of William Simpson.

• IPA^(key): /ˌɪdioʊˈpæθɪk/

idiopathic (not comparable)

1. (pathology) Of, relating to, or designating a disease or condition having no known cause.

   Synonyms: essential, primary, agnogenic

   • 2014 January 20, Simona Supekar, “How the Internet Helped Me Cope With My Rare Disease”, in The Atlantic‎^[1]:

     So when I was diagnosed with a fairly difficult-to-treat disease called idiopathic angioedema and chronic urticaria (a fancy way of saying we don’t know why you swell and hey, enjoy the 24/7 hives) six months ago, I wasn't quite sure how to cope.

• idiopathy