reaction

noun
re·​ac·​tion | \ rē-ˈak-shən How to pronounce reaction (audio) \

Definition of reaction

1a : the act or process or an instance of reacting
b : resistance or opposition to a force, influence, or movement especially : tendency toward a former and usually outmoded political or social order or policy
2 : a response to some treatment, situation, or stimulus her stunned reaction to the news also : such a response expressed verbally critical reaction to the play
3 : bodily response to or activity aroused by a stimulus:
a : an action induced by vital resistance to another action especially : the response of tissues to a foreign substance (such as an antigen or infectious agent)
b : depression or exhaustion due to excessive exertion or stimulation
c : heightened activity and overaction succeeding depression or shock
d : a mental or emotional disorder forming an individual's response to his or her life situation
4 : the force that a body subjected to the action of a force from another body exerts in the opposite direction
5a(1) : chemical transformation or change : the interaction of chemical entities
(2) : the state resulting from such a reaction
b : a process involving change in atomic nuclei

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Synonyms for reaction

Synonyms

answer, reply, response, take

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Examples of reaction in a Sentence

Their reaction to the news was positive. When I told him what happened, his immediate reaction was one of shock. The announcement produced an angry reaction from most of the people at the meeting. My first reaction when I met him was not to trust him. There hasn't yet been much reaction to the announcement. There has been strong reaction against the government's policies. A good driver has quick reactions. The speed of his reactions saved his life.
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Recent Examples on the Web

What the bills leave in place, however, is a defendant’s ability to claim that his own past trauma can explain the extreme reaction to a victim’s conduct. Jeannie Suk Gersen, The New Yorker, "The End of the Gay-Panic Legal Defense," 8 July 2019 The AfD’s reaction to the Lübcke tragedy seemed to confirm the party’s reputation. The Economist, "German soul-searching after the murder of a champion of refugees," 5 July 2019 Watch the videos above for more on the film, including Boyle’s unexpected reaction to Patel’s audition. Lauren Huff, EW.com, "Ed Sheeran won't let Danny Boyle forget he wasn't the director's first choice for Yesterday," 5 July 2019 Gohlke noted this year’s 50th anniversary of the Stonewall riots in New York City, a reaction to police harassment that many date as the beginning of the national movement for civil rights for the LGBTQ community. Brooke Lamantia, ExpressNews.com, "San Antonio Public Library houses an ‘Out and Proud’ exhibit to highlight pride," 5 July 2019 Andrei’s reaction to Mr. Trump came as no surprise. The Christian Science Monitor, "a new front for Chinese propaganda," 3 July 2019 Members of the group were also trading jokes in reaction to the news of a migrant’s death while in custody, ProPublica found. Kat Borgerding, Vox, "Recode Daily: Facebook’s auditors say the platform’s white supremacy ban is too narrow," 2 July 2019 The decision came in reaction to a lawsuit presented by opponents of the new system. Tad Vezner, Twin Cities, "St. Paul garbage system’s fate to be determined in August; MN Supreme Court hearing scheduled," 28 June 2019 The Puffs’ experiences are in reaction to key events in the series. Pomerado News, "REVIEW: ‘Puffs’ is magical fun for Harry Potter fans," 26 June 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'reaction.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of reaction

1585, in the meaning defined at sense 1a

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Statistics for reaction

Last Updated

11 Jul 2019

Look-up Popularity

Time Traveler for reaction

The first known use of reaction was in 1585

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More Definitions for reaction

reaction

noun

English Language Learners Definition of reaction

: the way someone acts or feels in response to something that happens, is said, etc.
: an action or attitude that shows disagreement with or disapproval of someone or something
: the ability to act and move quickly in order to avoid sudden danger

reaction

noun
re·​ac·​tion | \ rē-ˈak-shən How to pronounce reaction (audio) \

Kids Definition of reaction

1 : behavior or attitude in response to something What was your reaction to the news?
2 : a response of the body to a stimulus He had an allergic reaction to peanuts.
3 : a chemical change that is brought about by the action of one substance on another and results in a new substance being formed

reaction

noun
re·​ac·​tion | \ rē-ˈak-shən How to pronounce reaction (audio) \

Medical Definition of reaction

1 : the act or process or an instance of reacting
2 : bodily response to or activity aroused by a stimulus:
a : an action induced by vital resistance to another action especially : the response of tissues to a foreign substance (as an antigen or infectious agent)
b : depression or exhaustion due to excessive exertion or stimulation
c : abnormally heightened activity succeeding depression or shock
d : a mental or emotional disorder forming an individual's response to his or her life situation
3 : the force that a body subjected to the action of a force from another body exerts in the opposite direction
4a(1) : chemical transformation or change : the interaction of chemical entities
(2) : the state resulting from such a reaction
b : a process involving change in atomic nuclei

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Comments on reaction

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