illness

noun

ill·​ness ˈil-nəs 

1

a

: sickness sense 2

b

: an unhealthy condition of body or mind

2

obsolete

a

: wickedness

b

: unpleasantness

Synonyms of illness

• disease
• ailment
• ill
• sickness
• fever

Examples of illness in a Sentence

Her body was not able to defend itself against illness.

Hundreds of soldiers died from illness and hunger.

He showed no signs of illness.

Scientists have not yet found a cure for this illness.

cancer, diabetes, and other illnesses

She died at the age of 60 after a brief illness.

Recent Examples on the Web

To prove the effectiveness of thread-ectronic sensors, Sonkusale his team demonstrated how their innovation amplified subtle signals that could, in context, indicate stress, illness, and more. — New Atlas, 2 Aug. 2026

Kennedy also questioned the benefits of COVID-19 vaccines for children, despite extensive studies demonstrating their effectiveness in preventing severe illness. — Omer Awan, Forbes.com, 2 Aug. 2026

Eventually transitioning the conversation to measles, Bash, citing medical data, spoke about record-breaking cases of the illness among those who are unvaccinated. — Nicholas Rice, PEOPLE, 2 Aug. 2026

Now, the Grammy winner is offering details about that illness, especially about his battle with alcohol. — Tom Tapp, Deadline, 2 Aug. 2026

Word History

First Known Use

circa 1500, in the meaning defined at sense 2a

Phrases Containing illness

• bipolar illness
• illness anxiety disorder
• manic-depressive illness
• mental illness

Rhymes for illness

• stillness

Kids Definition

illness

noun

ill·​ness ˈil-nəs 

1

: an unhealthy condition of body or mind

2

: sickness sense 2

Medical Definition

illness

noun

ill·​ness ˈil-nəs 

: an unhealthy condition of body or mind : sickness