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

All these conversations are being had now because of King Charles’ illness. —Lizzie Lanuza, StyleCaster, 21 July 2025

Hospitals will close, Americans will go hungry and die of preventable illnesses, but at least there will be far more detention space for our neighbors. —New York Daily News Editorial Board, New York Daily News, 20 July 2025

Their demeanors never changed, the injuries and illnesses never diminished their love of the game or their love for the Mets. —Abbey Mastracco, Hartford Courant, 19 July 2025

Older adults, young children and people with chronic illnesses face the greatest risk from extreme heat. —Mandy Taheri, MSNBC Newsweek, 19 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