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 British royal family has been facing its fair share of drama lately, with King Charles’ illness taking center stage. —Lissete Lanuza Sáenz, StyleCaster, 9 July 2025

There have been no injuries or illnesses reported to Mondelēz Global to date. —Chad Murphy, The Enquirer, 9 July 2025

Having more information about the effects of injury, age, and disease on human cells can help researchers understand how cancers and other illnesses form, potentially contributing to new therapies. —semafor.com, 9 July 2025

Similarly, disability insurance replaces your income if injury or illness prevents you from working for an extended period. —True Tamplin, Forbes.com, 9 July 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