illness
Americannoun
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illnesses
plural
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poor health; sickness.
He grew up in an environment known for poverty, illness, and little opportunity for education.
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a specific sickness or disease, or an instance of such.
Please be as accurate as possible in listing your childhood illnesses.
- Synonyms:
- infirmity, affliction, ailment
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Obsolete. wickedness.
noun
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a disease or indisposition; sickness
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a state of ill health
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obsolete wickedness
Usage
What does illness mean? Illness is a state of poor health or sickness, as in I’ve had to miss a lot of work due to illness. The word illness is also commonly used to refer to a disease or instance of sickness. This sense of the word is often used when the type of disease is uncertain or unknown or when someone doesn’t want to specify what it is, as in They said that he is in the hospital with an illness, but they didn’t provide any further details. The word illness is based on the adjective ill, meaning sick. Example: The best way to avoid illness is to thoroughly wash your hands.
Other Word Forms
Noun Inflected Forms
Etymology
Origin of illness
Compare meaning
How does illness compare to similar and commonly confused words? Explore the most common comparisons:
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Sullivan has argued that medical countermeasures should be developed more broadly for pathogens capable of causing severe illness or death in humans, rather than focusing only on viruses already known to cause frequent outbreaks.
From Science Daily ● Sep. 20, 2026
Palisades High athletic director Rocky Montz announced Thursday afternoon that the Dolphins have forfeited their nonleague football game at San Pedro on Friday night because of an illness outbreak.
From Los Angeles Times ● Sep. 17, 2026
Walker’s illness — which included seizures and frequent hospitalizations — prevented her from traveling out of state, said Molly Duane, one of the family’s attorneys.
From Salon ● Sep. 17, 2026
None of these are easy conversations to have, and few people like to think about illness and death.
From MarketWatch ● Sep. 14, 2026
The hospital’s previous building for mental illness had burned down when an inmate set it on fire, so patients were closely watched to make sure they didn’t cause trouble.
From "The Woman All Spies Fear" by Amy Butler Greenfield
Another major challenge is that Bundibugyo can initially resemble several far more common illnesses.
From Science Daily ● Sep. 20, 2026
Decide what kind of coverage suits you: Some plans cover accidents and illnesses, while wellness coverage may help pay for routine care such as checkups, dental cleanings and vaccines.
From MarketWatch ● Sep. 15, 2026
By July 16, federal officials had identified 1,644 illnesses among people who reported eating at the chain, with ingredient-level analysis strongly pointing to iceberg lettuce.
From Salon ● Sep. 13, 2026
In the more than two decades since the attacks, more people have died from related illnesses than those who were killed on that day, New York City Mayor Zohran Mamdani said.
From The Wall Street Journal ● Sep. 8, 2026
Marshall seemed content to sit and listen, so the game went on with daring adventures, narrow escapes, tragic illnesses and even a romance or two.
From "The Egypt Game" by Zilpha Keatley Snyder
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
