noun
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the act of polluting or the state of being polluted
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harmful or poisonous substances introduced into an environment
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The contamination of air, water, or soil by substances that are harmful to living organisms. Pollution can occur naturally, for example through volcanic eruptions, or as the result of human activities, such as the spilling of oil or disposal of industrial waste.
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◆ Light from cities and towns at night that interferes with astronomical observations is known as light pollution. It can also disturb natural rhythms of growth in plants and other organisms.
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◆ Continuous noise that is loud enough to be annoying or physically harmful is known as noise pollution.
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◆ Heat from hot water that is discharged from a factory into a river or lake, where it can kill or endanger aquatic life, is known as thermal pollution.
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Etymology
Origin of pollution
First recorded in 1350–1400; Middle English pollucioun, from Old French, from Late Latin pollūtiōn-, stem of pollūtiō “defilement”; equivalent to pollute + -ion
Explanation
Pollution is unwanted, harmful stuff contaminating an environment. The race to develop clean energy is motivated by high levels of pollution that people fear are permanently damaging the earth's environment. When you hear about pollution, you’re most likely hearing about chemical emissions into air or water that come from industrial processing. But pollution isn’t just environmental. Anything we think of as pure can be contaminated by pollution polluted, whether that's a lake or an idea. If your mother finds you reading trashy magazines instead of doing your homework, she might worry about the pollution of your mind.
Vocabulary lists containing pollution
Africa - Introductory
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Eastern Europe - Introductory
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East Asia - Middle School
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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.
Up to 45 percent of dementia risk could be prevented or delayed, the World Health Organization said Wednesday, citing modifiable risk factors such as tobacco and air pollution.
From Barron's ● Jul. 15, 2026
New Yorkers were warned by state authorities that they "may see visible smoke and hazy skies across the state and spikes in smoke-related pollution."
From Barron's ● Jul. 15, 2026
"The biggest contributor to Toronto's spike in air pollution right now is wildfires, though the higher than average temperatures are also playing a role," Armen Araradian of IQAir told AFP.
From Barron's ● Jul. 15, 2026
It was just one of 65 separate pollution incidents in rivers and waterways that have killed more than 50,000 fish in the last five years.
From BBC ● Jul. 14, 2026
Him: Light pollution makes naked eye stargazing suck here, but I can see all eight stars in the Big Dipper right now, if you include Alcor.
From "Turtles All the Way Down" by John Green
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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.