Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “reaction”

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)
What is the pronunciation of reaction?
Add Cambridge dictionaries to your browser to your website

Definitions of “reaction” in other dictionaries

Word of the Day

dawn on sb

If a fact dawns on you, you understand it after a period of not understanding it.

Word of the Day

The language of work

by Kate Woodford,
October 15, 2014
Most of us talk about our jobs. We tell our family and friends interesting or funny things that have happened in the workplace (=room where we do our job), we describe – and sometimes complain about – our bosses and colleagues and when we meet someone for the first time, we tell

Read More 

life tracking noun

October 20, 2014
the use of one or more devices or apps to monitor health, exercise, how time is spent, etc.

Read More