diagnostic

American  

[dahy-uhg-nos-tik] / ˌdaɪ əgˈnɒs tɪk /

adjective

1. of, relating to, or used in diagnosis.

2. serving to identify or characterize; being a precise indication.

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noun

1. diagnosis.

2. a symptom or characteristic of value in diagnosis.

3. Medicine/Medical. a device or substance used for the analysis or detection of diseases or other medical conditions.

4. Computers.

   1. a message output by a computer diagnosing an error in a computer program, computer system, or component device.

   2. a program or subroutine that produces such messages.

diagnostic British  

/ ˌdaɪəɡˈnɒstɪk /

adjective

1. of, relating to, or of value in diagnosis

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noun

1. med any symptom that provides evidence for making a specific diagnosis

2. a diagnosis

Other Word Forms

• diagnostically adverb
• postdiagnostic adjective
• prediagnostic adjective

Etymology

Origin of diagnostic

1615–25; < Greek diagnōstikós, equivalent to diagnōst ( ós ) distinguished (akin to diágnōsis; diagnosis ) + -ikos -ic

Explanation

Anything diagnostic has to do with disease, especially figuring out which one a patient has. If your doctor wants to run diagnostic tests, then she isn't exactly sure what's wrong with you — so the tests will help diagnose you (figure out what's wrong). The TV show House is all about diagnostic tests: it features illnesses that are unusual and hard to determine. But anything diagnostic is trying to figure out what's wrong. A writing test could be called diagnostic if it's trying to determine how good or bad your writing skills are.

Example Sentences

Initiatives such as the Child Mind Institute's Healthy Brain Network reflect this direction by providing large-scale brain imaging and behavioral data, along with free diagnostic evaluations for families.

From Science Daily • Apr. 9, 2026

Baffert said the filly appeared OK but would undergo diagnostic tests to be sure.

From Los Angeles Times • Apr. 4, 2026

"Wrinkly can be mean lots of things, so there's a lack of diagnostic language."

From Science Daily • Apr. 3, 2026

"Where a screening programme expands its eligibility, it is important that the associated infrastructure, including diagnostic capacity, workforce and any treatments that may be required, are aligned," it added.

From BBC • Mar. 31, 2026

“Psycho” had a sudden mental-ward reality about it, a systematic, diagnostic sound.

From "A Separate Peace" by John Knowles