idiopathic
/aɪˈdaɪəpæθɪk/Definitions
1. adjective
of or relating to a medical disorder or condition that has no known cause
“Her doctor couldn’t find any cause for her idiopathic condition, so they decided to run more tests.”
2. noun
a medical condition that has no known cause
“The doctor diagnosed her with an idiopathic illness, and they were still trying to figure out what caused it.”