idiopathic

Adjective

idiopathic (not comparable)

1. Of, relating to, or designating a disease or condition having no known cause.
   • 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.2014 January 20, Simona Supekar, “How the Internet Helped Me Cope With My Rare Disease”, in The Atlantic, archived from the original on 29 Mar 2014
   • Juvenile rheumatoid arthritis (JRA), often referred to by doctors today as juvenile idiopathic arthritis (JIA), is a type of arthritis that causes joint inflammation and stiffness for more than six weeks in a child aged 16 or younger. It affects approximately 50,000 children in the United States....2024 September 6, David Zelman, “Understanding Juvenile Rheumatoid Arthritis -- the Basics”, in WebMD

   Synonyms:

   cryptogenic, essential, primary, agnogenic