diagnose

verb

di·​ag·​nose ˈdī-ig-ˌnōs 

-ˌnōz, 

ˌdī-ig-ˈnōs 

-ˈnōz, 

-əg-

diagnosed; diagnosing

transitive verb

1

a

: to recognize (something, such as a disease) by signs and symptoms

The other method of diagnosing gallstones is through an ultrasound examination, which has the advantages of being simple, safe and quick.

—G. Timothy Johnson

Pulmonary embolus was diagnosed in two of the actively treated patients …

—Richard D. Sautter et al.

b

: to recognize a disease or condition in

The physicist and cosmologist was diagnosed with Lou Gehrig's disease when he was a 21-year-old student at Cambridge University.

—Maria Cheng

2

: to analyze the cause or nature of

The mechanic diagnosed the problem with the engine.

intransitive verb

: to identify a disease from its signs and symptoms : to make a diagnosis

diagnosable adjective

or diagnoseable

ˌdī-ig-ˈnō-sə-bəl 

-əg-, 

-zə-

Examples of diagnose in a Sentence

The test is used to help in diagnosing heart disease.

Thousands of new cases have been diagnosed in the past year.

The doctor was unable to diagnose the skin condition.

a new doctor with little experience diagnosing patients

The mechanic was unable to diagnose the problem.

Recent Examples on the Web

It is diagnosed with a blood test and can be treated with medication. —Joyann Jeffrey, PEOPLE, 11 Apr. 2026

Philadelphia 76ers star Joel Embiid has been diagnosed with appendicitis and underwent surgery Thursday afternoon in Houston, the team announced. —Tony Jones, New York Times, 10 Apr. 2026

According to the American Cancer Society, about one in eight men will be diagnosed with prostate cancer during their lifetimes. —ABC News, 10 Apr. 2026

Scheffler’s most personal philanthropic work traces back to a childhood friendship with James Ragan, a fellow junior golfer in Texas who was diagnosed with osteosarcoma in 2006. —Sydney Lake, Fortune, 10 Apr. 2026

Word History

Etymology

back-formation from diagnosis

First Known Use

circa 1841, in the meaning defined at transitive sense 1a

Rhymes for diagnose

• adios
• adipose
• amylose
• bellicose
• cellulose
• centavos
• comatose
• grandiose
• granulose
• levulose
• overdose
• ribulose

Kids Definition

diagnose

verb

di·​ag·​nose ˈdī-ig-ˌnōs  -ˌnōz 

ˌdī-ig-ˈnōs, 

-ˈnōz

diagnosed; diagnosing

: to recognize by signs and symptoms : make a diagnosis

diagnose a disease

diagnose a play in football

Medical Definition

diagnose

verb

di·​ag·​nose ˈdī-ig-ˌnōs  -ˌnōz 

ˌdī-ig-ˈ, 

-əg-

diagnosed; diagnosing

transitive verb

1

: to recognize (as a disease) by signs and symptoms

2

: to diagnose a disease or condition in

diagnosed the patient

intransitive verb

: to make a diagnosis

diagnosable adjective

also diagnoseable

ˌdī-ig-ˈnō-sə-bəl, -əg-, -zə-