side effect
Americannoun
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side effects
plural
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any effect of a drug, chemical, or other medicine that is in addition to its intended effect, especially an effect that is harmful or unpleasant.
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any accompanying or consequential and usually detrimental effect.
the side effects of air pollution.
noun
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any unwanted nontherapeutic effect caused by a drug Compare aftereffect
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any secondary effect, esp an undesirable one
Other Word Forms
Noun Inflected Forms
Etymology
Origin of side effect
First recorded in 1880–85
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.
That’s an inevitable side effect of appearing on a Bill Lawrence show.
From Los Angeles Times ● Aug. 10, 2026
A wave of artificial-intelligence adoption has come with an undesirable side effect: An explosion of cyberthreats.
From MarketWatch ● Aug. 2, 2026
Sam experienced one bout of excruciating pain a week after the procedure, a known but uncommon side effect of vasectomies according to Dr Salkeld, but that subsided after a few hours.
From BBC ● Aug. 1, 2026
Another potential side effect is an increase in the number of red blood cells.
From The Wall Street Journal ● Jul. 31, 2026
It wasn't the point of the paper chain, but it was a great side effect.
From "Linked" by Gordon Korman
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.
