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:
Vaccines prevent serious illness for many people, but the immune protection they produce can differ substantially from one person to another.
From Science Daily ● Aug. 21, 2026
There is no specific treatment for the disease nor a vaccine to prevent illness.
From Los Angeles Times ● Aug. 21, 2026
Oura gathers a range of health data including heart rate and sleep patterns and uses them to develop predictions and personalized insights in areas such as impending illness and menstrual cycles.
From The Wall Street Journal ● Aug. 20, 2026
In 2024, Buckingham Palace made Charles’ cancer diagnosis public without specifying the severity of his illness.
From Salon ● Aug. 20, 2026
I used my knowledge of this phase of spiritual pathology, and laid down a rule that she should not be present with Lucy or think of her illness more than was absolutely required.
From "Dracula" by Bram Stoker
The Minneapolis-based company, which also sells under the Calco brand, said it hasn’t received any reports of illnesses involving the sprouts.
From The Wall Street Journal ● Aug. 21, 2026
Many factors can influence vaccine response, including age, sex, genetics, previous illnesses and underlying health conditions.
From Science Daily ● Aug. 21, 2026
It is among the most serious illnesses a woman can experience after giving birth, experts told the BBC, but it remains unclassified in medicine's encyclopaedia of psychiatry.
From BBC ● Aug. 19, 2026
Officials in Michigan, one state with a disproportionately large number of illnesses, said earlier this month that it had become safer to eat lettuce and salad greens as case counts started to fall.
From MarketWatch ● Aug. 18, 2026
The old marks of accidents and bad food and childhood illnesses all washed away.
From "Uglies" by Scott Westerfeld
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.
