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

If anyone shows signs of heat illness, promptly move them to a cool, shaded area. — Nc Weather Bot, Charlotte Observer, 5 July 2026

This could be a sign of an impending health issue like a viral illness. — Nicole Williams, AJC.com, 6 July 2026

Those with heart disease and respiratory illnesses, young children and older adults are more at risk. — Lauren Penington, Denver Post, 5 July 2026

Whatever happened—injury, illness, flood, or drought—felt preordained, part of God’s grand scheme. — The New Yorker, New Yorker, 4 July 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