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

Breeds with breathing issues — including bulldogs, pugs, boxers, Boston terriers and Persian cats — are also more susceptible to heat illness, state health officials said. —Sacbee.com, 10 June 2026

This can increase the risk of obesity, diabetes, heart disease, dementia and other chronic illnesses. —Melissa Rudy, FOXNews.com, 10 June 2026

The most impressive thing about his set, however, may have been how little the illness seemed to affect his performance. —Théoden Janes, Charlotte Observer, 10 June 2026

Lawmakers had previously given state health officials the authority to conduct visits to the facility, and the Adams County Health Department launched an investigation into the facility earlier this year after immigrant advocates alleged that gastrointestinal illness was rampant. —Seth Klamann, Denver Post, 9 June 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