diagnosis /daɪəɡˈnəʊsɪs/noun 3verb 1forms 1 noun3 •The process of, or an instance of, identification of the nature and cause of a medical condition or illness.Diagnosis is a challenging art informed by wide-ranging science.He was given the wrong treatment due to an erroneous diagnosis. •The process of, or an instance of, identification of the nature and cause of something (of any nature).Diagnosis is part of being an automotive mechanic.Her diagnosis of the current economic situation is that central banks are overcorrecting. •A written description of a species or other taxon serving to distinguish that species from all others; especially a description written and published in Latin. verb1 •(nonstandard, rare) Synonym of diagnose.Experienced mechanics can diagnosis the condition of machinery just by listening. — 2013 formsdiagnoses