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

• 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 queen mother died last week at the age of 93 after years battling illnesses, Reuters reported. —Michael Cappetta, Travel + Leisure, 30 Oct. 2025

In rare cases, if the illness looks unusual or severe, the clinician may collect a throat swab or stool sample to test for the specific virus. —Katia Hetter, CNN Money, 29 Oct. 2025

Each quarter, the department releases a report that details injuries and illnesses at exempt facilities. —Colson Thayer, PEOPLE, 29 Oct. 2025

Soon, each member of the family is targeted by evil forces, none testing their fate more so than their living son Caleb's (Harvey Scrimshaw) unusual illness. —Michael Lee Simpson, Entertainment Weekly, 29 Oct. 2025

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