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English definition of “reaction”

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reaction

noun [C]  /riˈæk·ʃən/ us  
behavior, a feeling, or an action that is a direct result of something else: My initial reaction was to call off the party. Senator, what is your reaction to the proposal to cut Medicare benefits? A reaction is also a change that opposes a previous opinion or behavior: His art is a reaction against photographic realism. biology A reaction can also be an unpleasant effect on the body resulting from something eaten or taken, such as a drug. chemistry A chemical reaction is the change that happens when two or more substances are mixed with each other.
(Definition of reaction from the Cambridge Academic Content Dictionary © Cambridge University Press)
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