Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “reaction”

See all translations

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.
More examples

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)
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

luck out

to be very lucky

Word of the Day

Think long and hard; the language of decisions

by Liz Walter,
January 28, 2015
One of the best ways (perhaps the best way) to improve your English is to learn how words go together in phrases, idioms, or other patterns such as verb/noun or adjective/noun pairs (often called ‘collocations’). This blog looks at some useful phrases and collocations connected with the subject of decisions, something we

Read More 

micro pig noun

January 26, 2015
an extremely small pig, bred to be a pet Micro pigs have become popular pets recently, with famous owners including Victoria Beckham, Paris Hilton and Olympic diver, Tom Daley.

Read More