[ dahy-uhg-nohs, -nohz, dahy-uhg-nohs, -nohz ]
See synonyms for: diagnosediagnosed on Thesaurus.com

verb (used with object),di·ag·nosed, di·ag·nos·ing.
  1. to determine the identity of (a disease, illness, etc.) by a medical examination: The doctor diagnosed the illness as influenza.

  2. 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.

  1. to classify or determine on the basis of scientific examination.

verb (used without object),di·ag·nosed, di·ag·nos·ing.
  1. to make a diagnosis.

Origin of diagnose

First recorded in 1860–65; back formation from diagnosis

Other words from diagnose

  • di·ag·nos·a·ble, adjective
  • un·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, adjective
  • un·di·ag·nosed, adjective
  • well-di·ag·nosed, adjective

Words Nearby diagnose

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use diagnose in a sentence

British Dictionary definitions for diagnose


/ (ˈdaɪəɡˌnəʊz) /

  1. to determine or distinguish by diagnosis

  2. (tr) to examine (a person or thing), as for a disease

Derived forms of diagnose

  • diagnosable, 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