1. Identification of a disease, syndrome, or condition by scientific evaluation of history, physical signs, symptoms, tests, and procedures. Diagnosis includes the technical description of the disease or condition and its cause, as well as the proper diagnostic code from the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code book. 2. In Medicare fraud, misrepresenting the diagnosis for the patient to justify the service provided or equipment furnished.