What does diagnosis mean?
A diagnosis is the identification of the nature of something — most often a disease or medical condition, determined by examining its signs, symptoms, and test results. The term also applies beyond medicine to any careful analysis aimed at uncovering the root of a problem, as when engineers make a diagnosis of a mechanical fault or consultants diagnose weaknesses in an organization. The word comes from Greek, combining dia ('through') and gnosis ('knowledge'), and entered English in the early modern period through learned medical writing. Its plural is diagnoses. Closely related words include diagnose, diagnostic, and diagnostics. A useful contrast is with prognosis: a diagnosis tells you what is wrong, while a prognosis predicts how it is likely to unfold. Because accuracy matters enormously in its core sense, diagnosis carries connotations of expertise and precision, which is why the word lends authority even when applied figuratively to non-medical situations.
The identification of the nature of an illness or problem by examination of its characteristic features; also, the formal statement of such an identification.
"A correct diagnosis is essential before effective treatment can begin."
Pluralized as 'diagnoses'. Commonly paired with verbs such as make, reach, confirm, or receive.
An analysis of the cause or nature of a non-medical problem or situation.
"The consultant's diagnosis of the company's supply-chain problems proved accurate."
The plural follows the Greek-style -es ending, pronounced /-siːz/. It is standard in both British and American English.
"The clinic handled hundreds of diagnoses last year."
The word 'diagnosis' literally means 'knowing through' — from Greek dia ('through') and gnosis ('knowledge') — so every diagnosis is, etymologically, knowledge gained by seeing through to the heart of a problem.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of diagnosis
Diagnosis derives from Greek diagignōskein, meaning 'to distinguish' or 'to know thoroughly', formed from dia ('through') and gnōsis ('knowledge'). The noun passed into English via New Latin in the 17th century as part of the vocabulary of scientific medicine. It shares its Greek root gnōsis with words such as prognosis, agnostic, and gnostic.
Related word forms
How diagnosis is actually used
Primarily used in medical and clinical contexts but extends figuratively to any careful analysis of problems. Plural is 'diagnoses'. In medicine, a distinction is often drawn between diagnosis (what is wrong) and prognosis (what will happen).
Easily confused with diagnosis
A diagnosis identifies what condition someone has, while a prognosis predicts how that condition is likely to develop or resolve.