diagnostic

Etymology

It is borrowed from Ancient Greek διαγνωστικός (diagnōstikós, “able to distinguish”),^[2][3][4] from διαγνωστός (diagnōstós, “distinguishable”), the verbal adjective of διαγιγνώσκω (diagignṓskō, “to distinguish, discern”),^[2][5][6] from διά (diá, “apart, between”) and γιγνώσκω (gignṓskō, “to come to know”), from Proto-Indo-European *ǵneh₃- (“to know”).^[2] The noun goes back to the Greek phrase διαγνωστική (diagnōstikḗ) (with τέχνη (tékhnē) understood), "the art of distinguishing diseases".^[4][7][8] The OED compares French diagnostique, used in French in the 17th century.^[4]

Earliest recorded meaning

Relating to diagnosis, as an adjective, and diagnosis itself, as a noun: both in 1625, in J. Hart's Anatomie of Urines.^[4][6]

Semantic evolution

From the 1640s and 1650s the word described a symptom or trait that marks one disease, or one kind of plant or animal, off from others: a diagnostic is a distinctive sign.^[4][8] The biological use of the adjective is recorded from 1862.^[4] In the 1950s computing took the medical idea over for programs that find faults in a system (1953) and for the messages they produce (1963), part of a wider transfer of words from healing to computing in the second half of the 20th century.^[4][9]

Timeline

• 1625 – of diagnosis; also as a noun, diagnosis.^[4][6]
• 1646 – a distinguishing characteristic, in general use.^[4]
• 1651 – a distinctive symptom of a disease.^[4]
• 1862 – in biology, characteristic of a species or group.^[4]
• 1953 – of a computer program, designed to find faults.^[4]
• 1962 – diagnostics in physics, methods for studying a plasma.^[4]
• 1963 – a computer message that helps identify an error.^[4]

Modern meaning

Adjective

1. Relating to or used in diagnosis: diagnostic tests.
2. Of a symptom or feature: distinctive enough to identify a disease or problem.
3. (biology) Characteristic of a particular species or group.
4. (computing) Of a program or routine: designed to detect and report faults.

Noun

1. A distinctive symptom or characteristic.
2. diagnostics: the practice or techniques of diagnosis.
3. A test, instrument or technique used in diagnosis.
4. (computing) A program that detects faults, or a message that it produces.

Word family

• diagnostically
• diagnostician
• diagnosticate
• immunodiagnostic
• postdiagnostic
• prediagnostic

Related words

• diagnosis
• prognostic
• agnostic
• gnostic
• know

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
3. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
4. ^ a b c d e f g h i j k l m n Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
5. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
6. ^ a b c Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
8. ^ a b Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
9. ^ Mapping Metaphor with the Historical Thesaurus, University of Glasgow, mappingmetaphor.arts.gla.ac.uk