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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well-diagnosedadjective
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undiagnosedadjective
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undiagnosableadjective
Conjugated Forms
Present
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have diagnosedperfect
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has diagnosedperfect 3rd person singular
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have been diagnosingperfect progressive
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are diagnosingprogressive
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is diagnosingprogressive 3rd person singular
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diagnosingparticiple
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diagnosessingular 3rd person
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am diagnosingprogressive 1st person singular
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has been diagnosingperfect progressive 3rd person singular
Past
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had diagnosedperfect
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diagnosedsimple
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were diagnosingprogressive plural
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was diagnosingprogressive singular
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had been diagnosingperfect progressive
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diagnosedparticiple
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
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
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.
Historically, adenomyosis has been a condition which is hard to diagnose, as a hysterectomy was the only way to properly analyse the womb.
From BBC • May 20, 2026
Media outlets elevate instant analysis from so-called “experts” eager to diagnose Secret Service failures.
From The Wall Street Journal • May 5, 2026
If your doctor hears a murmur while listening to your heart, he or she will likely order an echocardiogram—an ultrasound of the heart that allows a doctor to diagnose the disease and determine care.
From The Wall Street Journal • Apr. 25, 2026
Smartphones can be used to diagnose, assess and treat Parkinson’s disease.
From Salon • Apr. 23, 2026
The magnets kept shorting out for reasons the engineers were able to diagnose only after opening one up, when they discovered its cooling oil had been thoroughly contaminated by rust, metal shavings, and sediment.
From "Big Science" by Michael Hiltzik
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.
