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

Outside linebacker Anfernee Jennings also took the field after being absent, while center Garrett Bradbury (illness), defensive lineman Khyiris Tonga (foot) and offensive tackle Vederian Lowe (illness) remained out. —Andrew Callahan, Boston Herald, 8 Jan. 2026

Details regarding the illness were not immediately disclosed. —Angel Saunders, PEOPLE, 8 Jan. 2026

Broadway Cares/Equity Fights AIDS, the philanthropic heart of the Broadway community, unites theater lovers to make a lifesaving and life-affirming difference for people facing HIV/AIDS and other critical illnesses across the country. —Sarah Shachat, IndieWire, 8 Jan. 2026

Local pediatricians in the upstate region of South Carolina have also seen parents refuse vaccination for their children, even after direct experience with illness from measles. —Deidre McPhillips, CNN Money, 8 Jan. 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