di·​ag·​nose | \ ˈdī-ig-ˌnōs How to pronounce diagnose (audio) , -ˌnōz, ˌdī-ig-ˈnōs How to pronounce diagnose (audio) , -ˈnōz, -əg- \
diagnosed; diagnosing

Definition of diagnose

transitive verb

1a : to recognize (something, such as a disease) by signs and symptoms The other method of diagnosing gallstones is through an ultrasound examination, which has the advantages of being simple, safe and quick.— G. Timothy Johnson Pulmonary embolus was diagnosed in two of the actively treated patients …— Richard D. Sautter et al.
b : to recognize a disease or condition in The physicist and cosmologist was diagnosed with Lou Gehrig's disease when he was a 21-year-old student at Cambridge University.— Maria Cheng
2 : to analyze the cause or nature of The mechanic diagnosed the problem with the engine.

intransitive verb

: to identify a disease from its signs and symptoms : to make a diagnosis

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Other Words from diagnose

diagnosable or diagnoseable \ ˌdī-​ig-​ˈnō-​sə-​bəl How to pronounce diagnoseable (audio) , -​əg-​ , -​zə-​ \ adjective

Examples of diagnose in a Sentence

The test is used to help in diagnosing heart disease. Thousands of new cases have been diagnosed in the past year. The doctor was unable to diagnose the skin condition. a new doctor with little experience diagnosing patients The mechanic was unable to diagnose the problem.
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Recent Examples on the Web In response, Rai says that the Oura ring is in early stages of development and that the device’s primary use will be not to diagnose but to indicate when a player needs a second test. Eric Niiler, Wired, "Tech That Could Help Pro Sports Adapt to the Pandemic," 7 July 2020 Within days, doctors would also diagnose septic shock, respiratory failure, a lung infection and a host of other ailments. Peter Van Sant, CBS News, "Casey Kasem's wife, children accused each other of "killing" radio icon," 4 July 2020 Most molecular tests involve a nose or throat swab and are used to diagnose an active infection. Washington Post, "Puerto Rico to demand COVID-19 test results from passengers," 30 June 2020 The testing will not be the invasive deep nasal swabs that most healthcare facilities have used so far to diagnose the disease, but less invasive nasal swabs or saliva tests. Dennis Pillion | Dpillion@al.com, al, "Alabama to fund widespread COVID testing for college students this fall," 29 June 2020 According to Brian Fallon, director of Columbia University’s Lyme and Tick-Borne Diseases Research Center in New York, in areas where Lyme disease is less common, doctors have to rely much more heavily on positive test results to diagnose it. Carrie Arnold, Popular Science, "COVID-19 testing problems are all too familiar to Lyme disease patients," 28 June 2020 Keep in mind, supplement manufacturers cannot claim that their product will diagnose, cure, mitigate, treat or prevent a disease. Lisa Drayer, CNN, "Should you take a dietary supplement to prevent disease?," 24 June 2020 The handbook helps professionals diagnose mental illnesses and strongly influences everything from research to public policy to health insurance. Erin Blakemore, National Geographic, "How PTSD went from ‘shell-shock’ to a recognized medical diagnosis," 16 June 2020 Tests to diagnose viral infections are key to controlling the pandemic, but African countries do not make any locally and must import them. Sarah Wild, Scientific American, "African Countries Scramble to Ramp up Testing for COVID-19," 16 June 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'diagnose.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of diagnose

circa 1841, in the meaning defined at transitive sense 1a

History and Etymology for diagnose

back-formation from diagnosis

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Time Traveler for diagnose

Time Traveler

The first known use of diagnose was circa 1841

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Statistics for diagnose

Last Updated

10 Jul 2020

Cite this Entry

“Diagnose.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/diagnose. Accessed 13 Jul. 2020.

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More Definitions for diagnose


How to pronounce diagnose (audio) How to pronounce diagnose (audio)

English Language Learners Definition of diagnose

: to recognize (a disease, illness, etc.) by examining someone
: to recognize a disease, illness, etc., in (someone)
: to find the cause of (a problem)


di·​ag·​nose | \ ˈdī-əg-ˌnōs How to pronounce diagnose (audio) \
diagnosed; diagnosing

Kids Definition of diagnose

: to recognize (as a disease) by signs and symptoms The test is used for diagnosing strep throat.


di·​ag·​nose | \ ˈdī-ig-ˌnōs How to pronounce diagnose (audio) , -ˌnōz How to pronounce diagnose (audio) , ˌdī-ig-ˈ, -əg- \
diagnosed; diagnosing

Medical Definition of diagnose

transitive verb

1 : to recognize (as a disease) by signs and symptoms
2 : to diagnose a disease or condition in diagnosed the patient

Other Words from diagnose

diagnosable also diagnoseable \ ˌdī-​ig-​ˈnō-​sə-​bəl, -​əg-​, -​zə-​ How to pronounce diagnoseable (audio) \ adjective

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