[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 undiagnosed

Contemporary Examples of undiagnosed

Historical Examples of undiagnosed

  • Frequently this undiagnosed dement has satisfied himself with a weak, cynical philosophy that life is not worth while.

    Benign Stupors

    August Hoch

  • Ivan Fitzgerald finally isolated the germ that had caused the Finchley girl's undiagnosed illness.


    H. Beam Piper

  • By this time, our yaws and Jack's undiagnosed illness were so bad that we were anxiously waiting for the steamer.

  • Jason had an undiagnosed example of that when he got only part of his man back from the Valley of Kings.

    Zero Data

    Charles Saphro

British Dictionary definitions for undiagnosed



(of a medical condition, a problem, etc) not having been identified



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 undiagnosed



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

Online Etymology Dictionary, © 2010 Douglas Harper

undiagnosed 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.