From Latin diagnōsis, from Ancient Greek διάγνωσις, from διαγιγνώσκω ("to discern"), from διά ("through") + γιγνώσκω.

• IPA: /daɪəɡˈnəʊsɪs/

diagnosis

1. (medicine, countable, uncountable) The process of, or an instance of, identification of the nature and cause of an illness.

   Diagnosis is a challenging art informed by wide-ranging science.

   He was given the wrong treatment due to an erroneous diagnosis.

   Her diagnoses include type 2 diabetes mellitus, primary hypertension, diabetic retinopathy, and generalized anxiety disorder.

2. 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.

   • 1887, Charles L. Reade, Compton Reade, Charles Reade, Dramatist, Novelist, Journalist: A Memoir:

     The quick eye for effects, the clear diagnosis of men's minds, and the love of epigram.

   • 1887, James Payn, Glow-worm tales:

     My diagnosis of his character proved correct.

3. (taxonomy) 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.
   • 1992, Rudolf M[athias] Schuster, The Hepaticae and Anthocerotae of North America: East of the Hundredth Meridian, volume V, Chicago, Ill.: Field Museum of Natural History, →ISBN, page viii:

     The repeated exposure, over decades, to most taxa here treated has resulted in repeated modifications of both diagnoses and discussions, as initial ideas of the various taxa underwent—often repeated—conceptual modification.

• diagnose
• diagnostic
• diagnostics

• French: diagnostic, diagnose
• German: Diagnose
• Italian: diagnosi
• Portuguese: diagnóstico
• Russian: диа́гноз
• Spanish: diagnóstico, diagnosis

• German: Diagnose
• Russian: диа́гноз

• Portuguese: diagnose

1. (nonstandard, proscribed, rare) Synonym of diagnose
   • 2013, Donald A. Norman, The Design of Everyday Things:

     Experienced mechanics can diagnosis the condition of machinery just by listening.