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Synonyms

side effect

American  
Or side-effect

noun

  1. 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.

  2. any accompanying or consequential and usually detrimental effect.

    the side effects of air pollution.
side effect British  

noun

  1. any unwanted nontherapeutic effect caused by a drug Compare aftereffect

  2. any secondary effect, esp an undesirable one

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of side effect

First recorded in 1880–85

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.