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

The immediate illness known as Teflon flu is usually short-term, but PFAS exposure is part of a larger health debate. —Ryan Brennan june 2, Sacbee.com, 3 June 2026

The filing alleges Hubbard experienced gastrointestinal illness, sepsis, and other long-term complications, while the child reported nausea, vomiting, and abdominal distress. —Anthony Thompson, USA Today, 3 June 2026

Around the same time, he was diagnosed with Parkinson’s, the disease that ultimately contributed to his death from a respiratory illness. —Sarah Shephard, New York Times, 3 June 2026

Friends were lost to the disease, and surviving family members denied the illness or sometimes actively excluded partners from funerals. —Liz Tracey, JSTOR Daily, 3 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