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

Larsson has missed practice time and the final three preseason games because of his illness, and Smith missed the entire preseason after straining his calf during training camp. — Anthony Chiang, Miami Herald, 17 Oct. 2026

To be sure, practicing a zest for life can be harder for those who have physical illness and pain and those who engage in unhealthy lifestyle behaviors. — Joan M. Cook, Time, 17 Oct. 2026

Most cases resolve without antibiotics, but they may be used for severe illness or in settings with a higher transmission risk. — Charlotte Observer, 16 Oct. 2026

In Whalefall, written and directed by Brian Duffield, Jay (Abrams) goes diving in the Pacific Ocean to find the remains of his late father Mitt (Josh Brolin), who took his own life a year before amid a terminal illness. — Glenn Garner, Deadline, 16 Oct. 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