side effect
Americannoun
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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
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.
Tech Trader first began discussing the looming memory chip shortage back in December, as one more side effect of the booming market for artificial intelligence.
From Barron's • May 29, 2026
One side effect of the attacks is that dozens of patients—some with confirmed Ebola infections—fled the clinics and returned to their homes, risking further spread of the disease.
From The Wall Street Journal • May 26, 2026
Dandruff is a side effect of my medications, so I now use the same Head & Shoulders conditioner as my dad, which doesn’t help the middle-aged-man concern.
From Slate • May 23, 2026
Rather than simply being a side effect of growing larger bodies, the study suggests that shrinking arms were closely connected to the evolution of massive, powerful skulls and jaws.
From Science Daily • May 20, 2026
Now there’s a side effect of war I bet you never considered.
From "How I Live Now" by Meg Rosoff
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.
