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 of diagnostic

Adjective

• characteristic
• distinctive
• distinguishing
• distinct
• typical

Noun

• characteristic
• feature
• quality
• trait
• attribute
• attribution
• criterion

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

The company completed the spin-off of its biosciences and diagnostic solutions business in February. —Jim Cramer, CNBC, 10 Apr. 2026

Conventional diagnostic pathways often have long waitlists and multiple clinic visits. —Gretchen Wittenmyer-Stone, Kansas City Star, 10 Apr. 2026

Noun

Potential applications include environmental monitoring, food safety testing, and basic health diagnostics in low-resource settings. —Neetika Walter, Interesting Engineering, 17 Apr. 2026

Advanced diagnostics such as ultrasound, fetal monitoring, and genetic screening are employed to assess the health of both mother and baby. —Memorialcare Saddleback Medical Center, Oc Register, 16 Apr. 2026

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