overdiagnose

over- +‎ diagnose

overdiagnose (third-person singular simple present overdiagnoses, present participle overdiagnosing, simple past and past participle overdiagnosed)

1. (medicine) To diagnose something more often than it actually occurs.
2. (medicine) To diagnose something that never would have led to symptoms.
   • 2009, January 11, “Jeanne Dorin Mcdowell”, in The Four (at Least) Faces of Tara‎:

     Dissociative identity disorder is a contentious diagnosis: some professionals say the disorder is overdiagnosed; others say it doesn't even exist.

3. (medicine) To diagnose as a clinical case what is truly a subclinical case.