[dahy-uh g-nohs, -nohz, dahy-uh g-nohs, -nohz]

verb (used with object), di·ag·nosed, di·ag·nos·ing.

to determine the identity of (a disease, illness, etc.) by a medical examination: The doctor diagnosed the illness as influenza.
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.
to classify or determine on the basis of scientific examination.

verb (used without object), di·ag·nosed, di·ag·nos·ing.

to make a diagnosis.

Origin of diagnose

First recorded in 1860–65; back formation from diagnosis
Related formsdi·ag·nos·a·ble, adjectiveun·der·di·ag·nose, verb (used with object), un·der·di·ag·nosed, un·der·di·ag·nos·ing.un·di·ag·nos·a·ble, adjectiveun·di·ag·nosed, adjectivewell-di·ag·nosed, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for diagnosed

Contemporary Examples of diagnosed

Historical Examples of diagnosed

  • "Injun's on top," he diagnosed sententiously after a minute.

    Good Indian

    B. M. Bower

  • At Rossi's request Dr. Fedi had been called in, and he had diagnosed the case exactly.

  • The doctor was sent for and diagnosed the case "bilious fever."

  • I have, and I have diagnosed it as a case of mistaken identity.

    Whispering Smith

    Frank H. Spearman

  • "I said I had just diagnosed it, not that it had just started, señor," corrected Sanchez.


    Charles Louis Fontenay

British Dictionary definitions for diagnosed



to determine or distinguish by diagnosis
(tr) to examine (a person or thing), as for a disease
Derived Formsdiagnosable, adjective
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

Word Origin and History for diagnosed



1861, back-formation from diagnosis. Related: Diagnosed; diagnosing.

Online Etymology Dictionary, © 2010 Douglas Harper

diagnosed in Medicine


[dīəg-nōs′, -nōz′]


To distinguish or identify a disease by diagnosis.
To identify a person as having a particular disease or condition by diagnosis.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.