reaction

noun
re·ac·tion | \rē-ˈak-shən \

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 infective 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

As expected, there has been a reaction on the part of the public to this announcement. Allan Vought, The Aegis, "Concerned over reaction to water rate increase request, Bel Air officials take proactive approach," 3 July 2018 Your first reaction to this story may be to laugh, and that’s OK. Alysha Tsuji, For The Win, "Phillies fan an amazingly good sport after being injured by hot dog in freak accident," 20 June 2018 And that triggered a remarkable reaction from some of the Russian scientists who had led efforts that resulted in three of the elements. Edwin Cartlidge, Scientific American, "The Battle Behind the Periodic Table’s Latest Additions," 13 June 2018 Most analysts had expected that District Judge Richard Leon would rule in favor of the companies and strike down a Justice Department’s lawsuit to block the deal, which may have muted some of the immediate reaction. Aaron Pressman, Fortune, "Who Wall Street Sees as Winners and Losers in the AT&T-Time Warner Verdict," 12 June 2018 The additional nitrogen adds density to the molecule, and removing carbon helps balance out the oxidizer so all of the fuel can be used up to produce energy in the reaction. Jay Bennett, Popular Mechanics, "So Long TNT, There's a New Explosive in Town," 2 July 2018 The reaction was divisive, to say the least, but Russell was a fan. Lesley Goldberg, The Hollywood Reporter, "Inside the 'Felicity' 20-Year Reunion at ATX Festival," 10 June 2018 They are created in nuclear reactions – at power plants, in the center of the sun, and amid even more extreme events – when protons accelerate, collide and then shatter in a shower of energetic particles. Author: Sarah Kaplan, Anchorage Daily News, "In a cosmic first, scientists detect ‘ghost particles’ from a distant galaxy," 12 July 2018 This reaction has shaken my opinion of many people. Wendy Dent, WIRED, "The Engineering Behind Elon Musk's Bid to Save Thailand's Cave Boys," 11 July 2018

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

17 Oct 2018

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

reactions : the ability to act and move quickly in order to avoid sudden danger

reaction

noun
re·ac·tion | \rē-ˈak-shən \

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 \

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 infective 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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to reject or criticize sharply

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