diagnostic

1 of 2

adjective

di·​ag·​nos·​tic ˌdī-ig-ˈnä-stik 

-əg-

variants or less commonly diagnostical

ˌdī-ig-ˈnä-sti-kəl 

-əg-

1

a

: of, relating to, or used in diagnosis

a diagnostic tool

b

: using the methods of or yielding a diagnosis

diagnostic tests

2

: serving to distinguish or identify

a diagnostic feature

diagnostically

ˌdī-ig-ˈnä-sti-k(ə-)lē 

-əg-

adverb

diagnostic

2 of 2

noun

1

: the art or practice of diagnosis

—often used in plural

2

: a distinguishing mark

diagnostician

ˌdī-ig-(ˌ)nä-ˈsti-shən 

-əg-

noun

Synonyms

Adjective

• characteristic
• classic
• discriminating
• distinct
• distinctive
• distinguishing
• identifying
• individual
• peculiar
• proper
• symptomatic
• typical

Noun

• affection
• attribute
• attribution
• character
• characteristic
• criterion
• differentia
• feature
• fingerprint
• hallmark
• mark
• marker
• note
• particularity
• peculiarity
• point
• property
• quality
• specific
• stamp
• touch
• trait

Examples of diagnostic in a Sentence

Adjective

Ultrasound is now widely used as a diagnostic tool.

One important diagnostic feature of this condition is a mild rash.

Noun

the thesis that moral decline is the infallible diagnostic of a decadent society

Recent Examples on the Web

Adjective

Your provider will review your medical history, discuss your symptoms, examine your scalp, and order diagnostic tests if warranted. —Cristina Mutchler, Verywell Health, 19 June 2025

Affective forecasting, the capacity to anticipate how interactions will affect one’s emotional state, can serve as a valuable diagnostic tool. —Benjamin Laker, Forbes.com, 19 June 2025

Noun

Leadership diagnostic: Is your AI strategy designed around your system—or despite it? —Vibhas Ratanjee, Forbes.com, 21 June 2025

Saudi Arabia’s Vision 2030 includes a goal to train more than 100,000 AI specialists by the end of the decade, aligning with a national AI strategy focused on large language models, health care diagnostics, and industrial automation. —Manal Albarakati, semafor.com, 20 June 2025

Word History

First Known Use

Adjective

1625, in the meaning defined at sense 1a

Noun

1625, in the meaning defined at sense 1

Rhymes for diagnostic

• acrostic
• agnostic
• encaustic
• prognostic
• caustic
• gnostic

Kids Definition

diagnostic

adjective

di·​ag·​nos·​tic

ˌdī-ig-ˈnäs-tik

: of, relating to, or used in diagnosis

a diagnostic test for heart disease

Medical Definition

diagnostic

1 of 2 adjective

di·​ag·​nos·​tic -ˈnäs-tik 

variants also diagnostical

-ti-kəl 

1

: of, relating to, or used in diagnosis

2

: using the methods of or yielding a diagnosis

a diagnostic service

diagnostic properties

diagnostically

-ti-k(ə-)lē 

adverb

diagnostic

2 of 2 noun

: the art or practice of diagnosis

—often used in plural