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

Their recent 2-0 away win over Levante has boosted confidence, and returning players such as midfielder Iñigo Ruiz de Galarreta (after suspension) and defender Aymeric Laporte (after illness) could strengthen their lineup. —Ben Verbrugge, MSNBC Newsweek, 3 Dec. 2025

The nature of the illness was not disclosed. —Shania Russell, Entertainment Weekly, 3 Dec. 2025

Chai's illness in kittenhood kept Anderson from pursuing her adventure cat dreams with the pet. —Kelli Bender, PEOPLE, 3 Dec. 2025

The city also encourages people to check on family members and friends who are at risk for injuries and illnesses with the cold, especially the elderly and people with certain medical conditions, and to limit time children and pets spend outdoors. —Kelli Arseneau, jsonline.com, 3 Dec. 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