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

Art Dlugach, a longtime sports producer for KPIX in San Francisco, died Thursday morning in Texas, surrounded by his family after a brief illness. —CBS News, 27 Mar. 2026

In turn, this means that people outside of Greater Boston can access high quality healthcare without having to drive for hours while battling illness. —Demetrius Atsalis, Boston Herald, 27 Mar. 2026

Insurance is also a good idea for travelers who are concerned about specific issues like illness, severe weather, or other travel disruptions, according to Morrow. —Jessica Puckett, Condé Nast Traveler, 27 Mar. 2026

The Department of Environmental Health and Quality issued a water closure because the sewage contained bacteria that could cause illness. —Point Loma-Ob Monthly, San Diego Union-Tribune, 27 Mar. 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