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

Shigellosis is a gastrointestinal illness caused by a group of bacteria called Shigella. — Devika Rao, TheWeek, 23 Oct. 2026

No illnesses have been reported so far, according to the recall notice. — Hali Smith, Idaho Statesman, 23 Oct. 2026

Likewise, the agents that cause illnesses such as COVID-19, influenza, mumps, pertussis, and strep throat can be transmitted as heavy droplets that land on mucous membranes. — Encyclopedia Britannica, 23 Oct. 2026

But genuinely funny moments are rare, badly outnumbered by done-to-death musings regarding the mysteries of being alive and torturous melodramatic moments in which Klara dully absorbs the severity of Josie’s illness and Chrissy’s sorrow. — Los Angeles Times, 22 Oct. 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