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
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.
Several Manhattan private-school parents said another key to getting extra time—and unlimited bathroom breaks—is enlisting a gastroenterologist to diagnose inflammatory bowel disease or irritable bowel syndrome.
From The Wall Street Journal • May 19, 2026
"It's a rare illness, it's hard to diagnose and easier to misdiagnose," he adds.
From BBC • May 6, 2026
Smartphones can be used to diagnose, assess and treat Parkinson’s disease.
From Salon • Apr. 23, 2026
She had suffered a similar mid-race seizure there but, because epilepsy is difficult to diagnose and seizures are often the only symptom, subsequent medical tests were unable to identify the cause.
From BBC • Apr. 23, 2026
“Yeah, true. Not that either of us could diagnose her without seeing her, but I suspect she’ll be home soon.”
From "Paper Towns" by John Green
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.
