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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.


noun

diagnostics plural
  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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

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

  2. a diagnosis

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

Derived Forms

Inflected Forms

Nouns

Etymology

Origin of diagnostic

1615–25; < Greek diagnōstikós, equivalent to diagnōst ( ós ) distinguished (akin to diágnōsis; see 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.

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Vocabulary lists containing diagnostic

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Diagnostic fees cover time, labor and materials, as well as the expertise required to identify the source of a problem.

From MarketWatch • Jun. 10, 2026

Diagnostic criteria remain unchanged for now, meaning the impact of the reclassification will depend heavily on whether medical practice follows the science.

From Salon • May 16, 2026

Burke told the court that social-media addiction isn’t listed in the Diagnostic and Statistical Manual of Mental Disorders, typically used by clinicians to diagnose mental illness.

From The Wall Street Journal • Feb. 26, 2026

Victor and Moses went through another Nairobi clinic, Universal Trends Medical and Diagnostic Centre, which declined to tell AFP the number of individuals referred by Global Face Human Resources.

From Barron's • Feb. 9, 2026

The so-called bible on the question of psychological illnesses is the Diagnostic and Statistical Manual of Mental Disorders, the DSM.

From "A Deadly Wandering: A Mystery, a Landmark Investigation, and the Astonishing Science of Attention in the Digital Age" by Matt Richtel

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