reaction
C1Neutral to formal
Definition
Meaning
A response to a stimulus or event, often an immediate feeling, thought, or action.
A process or change resulting from a stimulus, including chemical/biological processes, political/social movements opposing change, or a tendency toward a past state.
Linguistics
Semantic Notes
Often implies a response that is instinctive, emotional, or chemical rather than carefully considered. Can be neutral, positive, or negative depending on context.
Dialectal Variation
British vs American Usage
Differences
No significant lexical differences. 'Reaction on' (rare, dated) is occasionally found in older British texts, whereas 'reaction to' is standard in both. Political 'backlash' is more common than 'reaction' in US political journalism.
Connotations
In UK political contexts, 'reaction' can subtly imply a conservative or resistant response more readily than in US usage.
Frequency
Comparably high frequency in both varieties. Slightly higher in American academic (science) texts.
Vocabulary
Collocations
Grammar
Valency Patterns
reaction to + noun/gerund (e.g., reaction to the news)reaction against + noun (e.g., reaction against modernity)reaction from + noun (e.g., reaction from the public)reaction between + nouns (e.g., reaction between chemicals)Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “Chain reaction”
- “Gut reaction”
- “Knee-jerk reaction”
Usage
Context Usage
Business
Refers to market or customer response to a product, policy, or announcement.
Academic
Common in sciences (chemical/biological reaction) and social sciences (social/political reaction).
Everyday
Used for personal, emotional, or physical responses to events, news, or substances.
Technical
Precise term in chemistry, physics, and medicine (e.g., nuclear fission reaction, hypersensitivity reaction).
Examples
By Part of Speech
verb
British English
- (Not applicable - 'reaction' is a noun. The verb is 'react'.)
American English
- (Not applicable - 'reaction' is a noun. The verb is 'react'.)
adverb
British English
- reactionally (extremely rare)
American English
- reactionally (extremely rare)
adjective
British English
- reactionary (political context)
- reaction time
American English
- reactionary (political context)
- reaction time
Examples
By CEFR Level
- Her reaction was a big smile.
- I had a bad reaction to the medicine.
- What was his reaction to the film?
- The chemical reaction produced heat.
- The government's proposal met with a hostile reaction from the public.
- His initial knee-jerk reaction was to refuse the offer.
- The policy is widely seen as a reaction against the globalisation of the previous decade.
- The catalyst dramatically sped up the reaction rate.
Learning
Memory Aids
Mnemonic
Think of RE-ACTION: an ACTION taken again (re-) in response to a first action.
Conceptual Metaphor
INTERACTION IS A FORCE DYNAMIC (a force provokes an equal/opposite counter-force).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid translating Russian 'реакция' (as in 'reactionary politics') directly to 'reaction' in all contexts; for a political conservative, use 'reactionary'.
- Russian 'реакция' in chemistry is identical, but in emotional contexts, English 'reaction' is often more immediate/less considered than Russian 'реакция'.
- Do not use 'reaction' to mean 'reflex' (e.g., knee reflex) in medical contexts.
Common Mistakes
- Using 'reaction about' instead of 'reaction to'.
- Confusing 'reaction' (response) with 'reflection' (thought).
- Using it as a verb (incorrect: 'She reactioned badly'; correct: 'She reacted badly').
Practice
Quiz
In which context does 'reaction' most strongly imply resistance or opposition?
FAQ
Frequently Asked Questions
'Reaction' is often more immediate, instinctive, or emotional. 'Response' can be more deliberate, considered, or formal (e.g., an official response).
Yes, e.g., 'The product launch got a fantastic reaction from customers.' However, the word often carries a neutral or negative connotation unless specified as 'positive reaction'.
It is usually countable (a reaction, reactions). In scientific contexts, it can sometimes be uncountable when referring to the process (e.g., 'The rate of reaction is slow').
An 'allergic reaction' is a specific immune system response (can be severe). A 'side effect' is any secondary, typically undesired effect of a drug or treatment, which may not involve the immune system.
Collections
Part of a collection
Science and Technology
B1 · 47 words · Basic scientific concepts and modern technology.
Scientific Terminology
C1 · 44 words · Precise vocabulary used in scientific disciplines.