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

No chronic illness, no prescription medications, normal blood work and all that in my physical exams. —Carolyn Rosenblatt, Forbes.com, 27 June 2025

But then there are the rare illnesses that produce truly violent forces. —ArsTechnica, 27 June 2025

Unfortunately, sometimes listeria can spread into the brain and cause more serious illness, like meningitis. —Matthew Robinson, MSNBC Newsweek, 26 June 2025

In the new film Hot Milk, the sensual but diffident 20-something Sofia (Emma Mackey) travels with her invalid mother, Rose (Fiona Shaw), to the Mediterranean shores of Spain in search of an experimental cure for the latter’s (possibly hypochondriac) illness. —Erik Morse, Vogue, 26 June 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