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

The film follows poets Andrea Gibson and Megan Falley as their love deepens, and the couple finds newfound appreciation for the preciousness of life after a terminal illness diagnosis. —Addie Morfoot, Variety, 5 Nov. 2025

But babies, people with weakened immune systems, and those with chronic lung conditions are more likely to get seriously sick, developing illnesses like bronchiolitis or pneumonia. —Evan Moore november 5, Charlotte Observer, 5 Nov. 2025

Over the course of the show, a Greek chorus is forced to isolate from each other because of an infectious illness. —Senior Editor, MSNBC Newsweek, 5 Nov. 2025

When memory loss or illness enters the picture, every question can spark defensiveness or hurt. —Lauryn Higgins, Flow Space, 5 Nov. 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