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English definition of “reaction”

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reaction

noun uk   /riˈæk.ʃən/ us  

reaction noun (BEHAVIOUR)

B2 [C] behaviour, a feeling or an action that is a direct result of something else: I love to watch people's reactions when I say who I am. There has been an immediate/widespread/hostile reaction against the government's proposed tax increases. Reactions to the proposal so far have been adverse/favourable/mixed.reactions [plural] someone's ability to act quickly when something happens: You need to have quick reactions to play these computer games. [C usually singular] a type of behaviour or opinion that is produced or held with the intention of being different from something else: Her left-wing views are a reaction against the conservatism of her parents.
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reaction noun (UNPLEASANT EFFECT)

B2 [C] an unpleasant effect resulting from eating particular things or taking particular drugs: Some people have an allergic reaction to shellfish.

reaction noun (IN SCIENCE)

[C or U] chemistry an occasion when two or more substances react with and change each other: a chemical reaction

reaction noun (NO CHANGE)

[U] disapproving the belief or principle that there should be no social or political change, and the attempt to stop such change from happening: We must not allow reaction to stand in the way of progress.
(Definition of reaction from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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