reaction
gb/ɹiˈækʃən/ us/ɹiˈækʃən/
A2
English
~ 1300
Senses
0 senses
Noun
A2
event
1
A response to an action or event
Something you do, say, or feel after something happens.
Usage pattern:
[someone]'s reaction to [something]
Common mistake:
Learners sometimes confuse 'reaction' with 'opinion'. A reaction is immediate and often emotional; an opinion is a considered view.
Synonyms
response (More formal and neutral; often used in official contexts.)
Antonyms
indifference (Lack of emotional or active response to something.)
Collocations
strong reaction
|emotional reaction
|public reaction
|negative reaction
|immediate reaction
Themes
emotions
|communication
|daily life
Examples
- Her reaction to the news was one of shock.
- The teacher's reaction surprised the students.
- I was pleased by his positive reaction to my idea.
- Public reaction to the new law has been mixed.
Learner examples
- My reaction was slow.
- Her reaction was happy.
- He had a bad reaction to the movie.
- The reaction to the game was big.
Noun
technical
B1
event
2
A chemical change when substances interact
When two or more things mix and change into new things.
Usage pattern:
a chemical reaction between [substance] and [substance]
Common mistake:
Learners may confuse 'reaction' with 'mixture'. A mixture does not necessarily involve a chemical change.
Synonyms
process (General term for a series of changes; not specific to chemistry.)
Antonyms
stability (A state where no chemical change occurs.)
Collocations
chemical reaction
|violent reaction
|reaction rate
Themes
science
Examples
- The chemical reaction produced heat and light.
- Rusting is a slow chemical reaction.
- This experiment will demonstrate the reaction between vinegar and baking soda.
Learner examples
- Mixing these makes a big reaction.
- The reaction made gas.
- Heat starts the reaction.
Noun
B1
event
3
A body's physical response to something
How your body moves or changes when something happens to it.
Common mistake:
Learners may confuse 'reaction' with 'symptom'; a symptom is a sign of illness, while a reaction is the body's response to something specific.
Synonyms
reflex (An automatic movement in response to a stimulus; narrower than 'reaction'.)
Antonyms
tolerance (The body's ability to endure a stimulus without adverse effects.)
Collocations
allergic reaction
|skin reaction
|adverse reaction
Themes
health
|science
|body
Examples
- She had an allergic reaction to the medicine.
- The doctor checked his pupils' reaction to light.
- His quick reaction saved him from falling.
Learner examples
- I had a bad skin reaction.
- Her eyes had no reaction to light.
- The medicine gave me a strong reaction.
Noun
B2
state
4
Opposition to change or influence
When people do not want change and try to stop it.
Synonyms
resistance (Broad term for opposing force; not limited to societal change.)
Antonyms
acceptance (Willingness to accept new ideas or changes.)
Collocations
political reaction
|reaction against
Themes
politics
|society
|core_vocabulary
Examples
- There has been strong reaction against the policy changes.
- His ideas met with immediate reaction from traditionalists.
- The movement grew as a reaction to government reforms.
Learner examples
- People had a strong reaction against the plan.
- The law caused a big reaction in the town.
- His speech was a reaction to the new rules.
Grammar
Dictionary form
reaction
IPA
GB/ɹiˈækʃən/
US/ɹiˈækʃən/
Syllables & stress
re - ac - tion (3 syllables)
Stress on 2nd syllable (ac)
Word forms
Noun
- Base: reaction
- Plural: reaction, reactions
Word family
Expressions
delayed reaction
1/dɪlˈeɪd ɹiˈækʃən/
fixed phrase
A response that happens later than expected
When you answer or act some time after something happens.
Examples
- He had a delayed reaction to the joke and laughed minutes later.
- The medication can cause a delayed reaction in some patients.
gut reaction
1/ɡˈʌt ɹiˈækʃən/
fixed phrase
informal
An instinctive feeling-based response
A feeling about something that you have right away, without thinking much.
Examples
- My gut reaction was that something was wrong.
- Trust your gut reaction when making decisions.
chain reaction
1/t͡ʃˈeɪn ɹiˈækʃən/
fixed phrase
series of linked events caused by each other
A series of events where each one causes the next one to happen.
Examples
- The news set off a chain reaction of protests across the country.
- The argument set off a chain reaction in the office.
- One mistake led to a chain reaction of problems.
- One error in the system created a chain reaction of failures.
knee-jerk reaction
1/nˈi d͡ʒˈɚk ɹiˈækʃən/
idiom
Automatic unthinking response
A quick answer or action without thinking carefully.
Examples
- Her comment was just a knee-jerk reaction to criticism.
- Don't make a knee-jerk decision without considering the facts.
knee-jerk reaction
2/nˈi d͡ʒˈɚk ɹiˈækʃən/
idiom
informal
An immediate unthinking response
A quick answer or action without thinking carefully first.
Examples
- His comment was just a knee-jerk reaction to criticism.
- Don't make a knee-jerk reaction—think it over first.