IPA: //ˌdaɪəɡˈnɒstɪʃən//
KK: /daɪəɡˈnɑːstɪʃən/
A person who identifies diseases or conditions based on symptoms and tests, often a medical doctor.
The diagnostician was able to determine the cause of the patient's illness after several tests.
Diagnostician → It is formed from "diagnosis" (from Greek "diagnōsis", meaning discernment or judgment) and "-ician" (a suffix indicating a person skilled in a certain field). A diagnostician is a person skilled in the discernment or judgment of medical conditions.
Think of a diagnostician as someone who is skilled in making judgments about health conditions, where 'diagnosis' means discernment and '-ician' indicates a skilled person.