diagnose
Americanverb (used with object)
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to determine the identity of (a disease, illness, etc.) by a medical examination.
The doctor diagnosed the illness as influenza.
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to ascertain the cause or nature of (a disorder, malfunction, problem, etc.) from the symptoms.
The mechanic diagnosed the trouble that caused the engine knock.
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to classify or determine on the basis of scientific examination.
verb (used without object)
verb
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to determine or distinguish by diagnosis
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(tr) to examine (a person or thing), as for a disease
Other Word Forms
Derived Forms
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underdiagnoseverb (used with object)
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diagnosableadjective
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undiagnosableadjective
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undiagnosedadjective
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well-diagnosedadjective
Inflected Forms
Participles
Conjugated Forms
Present
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diagnosesimple
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diagnosessimple
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have diagnosedperfect
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has diagnosedperfect
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am diagnosingprogressive
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are diagnosingprogressive
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is diagnosingprogressive
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have been diagnosingperfect progressive
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has been diagnosingperfect progressive
Past
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diagnosedsimple
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had diagnosedperfect
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was diagnosingprogressive
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were diagnosingprogressive
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had been diagnosingperfect progressive
Future
Etymology
Origin of diagnose
First recorded in 1860–65; back formation from diagnosis
Explanation
If you diagnose a disease, you recognize it by the signs and symptoms your patient shows. Your high temperature and the green crud you keep coughing up will allow your doctor to diagnose your bronchitis. The verb diagnose was first used in medicine, meaning "make a diagnosis," or identify a disease by observation of symptoms. Use it to describe the process of figuring it out. If you have bad gut pain, ask your doctor to diagnose your condition. You can also use diagnose for other problems, like if you diagnose poverty and malnutrition as the real causes of a student's terrible behavior, or diagnose the virus that caused your computer to crash.
Vocabulary lists containing diagnose
100 Great Words from "Fahrenheit 451" -- Part I Vocabulary
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Mother's Day Words: What Mothers Do
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“About Edward Jenner” from the Jenner Institute
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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.
"Something that riles me is people say it's so much harder to diagnose women because they mask well," she say.
From BBC • Jul. 7, 2026
Currently, the main way to diagnose whether a patient has the disease on the NHS is through a surgical procedure called a laparoscopy, under general anaesthetic.
From BBC • Jul. 7, 2026
Start-up Wunderfix meanwhile offers repair services linking retailers, customers and shops via an application that allows cyclists to diagnose and, where possible, repair their bicycles themselves.
From Barron's • Jun. 28, 2026
The team says the findings could point to new ways to diagnose and treat Alzheimer's disease.
From Science Daily • Jun. 12, 2026
It took months for doctors to diagnose his ailment.
From "Hidden Figures" by Margot Lee Shetterly
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
