to event / situation
1 [C,U] ~ (to sb/sth) what you do, say or think as a result of sth that has happened:
What was his reaction to the news? * My immediate reaction was one of shock. * A spokesman said the changes were not in reaction to the company's recent losses. * There has been a mixed reaction to her appointment as director. * The decision provoked an angry reaction from local residents. * I tried shaking him but there was no reaction.
change in attitudes
2 [C,usually sing,U] ~ (against sth) a change in people's attitudes or behaviour caused by disapproval of the attitudes, etc. of the past:
The return to traditional family values is a reaction against the permissiveness of recent decades.
to drugs
3 [C,U] a response by the body, usually a bad one, to a drug, chemical substance, etc:
to suffer / have an allergic reaction to a drug
to danger
4 (reactions) [pl.] the ability to move quickly in response to sth, especially if in danger:
a skilled driver with quick reactions
against progress
5 [U] opposition to social or political progress or change:
The forces of reaction made change difficult.
science
6 [C,U] (technical) a chemical change produced by two or more substances acting on each other:
a chemical / nuclear reaction
seealsoCHAINREACTION
7 [U,C] a force shown by sth in response to another force, which is of equal strength and acts in the opposite direction:
Action and reaction are equal and opposite.
