react

react — verb

1. to take a particular action, express a feeling, or experience an emotion because

1.verbintransitiveB1
Definition

to take a particular action, express a feeling, or experience an emotion because of something that has just occurred, often without pausing to think.

Example

Sven reacted to the bad news by taking a deep breath and staying silent.

react + to [stimulus] + by [action]

When the fire alarm rang, Sayaka calmly helped her classmates leave the room.

Common collocations
  • react to [stimulus/situation]
  • react by [doing something]
  • react with [emotion: anger, surprise, joy]
  • react calmly / angrily / strongly / badly
Synonyms
  • respond

    more deliberate and less automatic than 'react'; suggests thought before action

  • answer

    specifically verbal; used when someone replies to a question or call

  • retort

    implies a quick, sharp, or witty reply, often in an argument

Antonyms
  • ignore

    to deliberately not react or pay attention to something

Grammar Patterns

react + to + noun/pronoun

react + by + -ing form

react + with + emotion noun

Usage Note

Commonly takes the preposition 'to' to introduce the trigger, and 'by' + gerund to describe the action taken. The subject can be a person, an animal, or an abstract entity such as a market or organisation. An adverb of manner (calmly, angrily, strongly) often directly follows the verb.

Common Mistakes

How did she react the news?
How did she react to the news?
'react' cannot take a direct object; use the preposition 'to' before the trigger.

2. to undergo a chemical or physical change through exposure to another substance,

2.verbintransitiveB2
Definition

to undergo a chemical or physical change through exposure to another substance, typically yielding one or more different materials or giving off energy.

Example

When sodium metal is placed in water, it reacts very quickly and produces hydrogen gas.

react + with [substance] + produces [result]

The chemistry teacher showed how copper reacts with oxygen to form a dark coating.

react + with [substance] + to form [result]

Common collocations
  • react with [substance: acid, oxygen, water]
  • react together / violently / explosively
  • react to form [new substance]
  • prevent [substance] from reacting

Grammar Patterns

react + with + noun (substance)

react + to form + noun (result)

Usage Note

In scientific contexts, the preposition 'with' introduces the other substance involved. The result of the reaction is commonly introduced by 'to form' or a result clause starting with 'and'. This sense is often used in the passive or with cautionary verbs like prevent, stop, or avoid.

Common Mistakes

The acid reacted the metal.
The acid reacted with the metal.
In chemistry, 'react' takes the preposition 'with', not a direct object.

3. to behave in a way that shows resistance or disagreement towards rules, authorit

3.verbintransitiveB2
Definition

to behave in a way that shows resistance or disagreement towards rules, authority, traditions, or social expectations, often by refusing to follow them.

Example

Arjun reacted against his parents' wishes by studying music instead of medicine.

react + against [expectation/authority]

The school's strict dress code made many students react against it by wearing casual clothes.

react + against [rule] + by [action]

Common collocations
  • react against [authority / rules / expectations / traditions / oppression]
  • react against [something] by [doing something]
Synonyms
  • rebel

    stronger than 'react against'; implies active, determined defiance

  • resist

    focuses on the act of withstanding or fighting back, often less emotional

  • push back

    informal; suggests a less organised or less intense form of opposition

Antonyms
  • accept

    to comply with rules or expectations rather than oppose them

  • conform

    to follow accepted rules, standards, or social norms

Grammar Patterns

react + against + noun/pronoun

Usage Note

Requires the preposition 'against' to introduce the target of opposition. Distinguish from Sense 1: 'react to' means simply 'respond', whereas 'react against' specifically implies resistance or defiance. Common in political, social, and generational contexts.

Common Mistakes

Teenagers often react to strict parents by staying out late.' (when meaning 'oppose').
Teenagers often react against strict parents by staying out late.
Use 'react against' for opposition; 'react to' simply means 'respond'.
Phrasal verbs

react against

phrasal verb

To show disagreement or opposition to something by behaving in a different way.

Teenagers often react against strict rules at home.

The workers reacted against the new policy by going on strike.

Word family

Synonym discussion

Sense: verb/1

'React' and 'respond' both refer to doing something as a result of a situation, but they differ in speed and deliberation. 'React' emphasises an immediate, often emotional or instinctive action — you react before you think. 'Respond' is more measured and considered: a firefighter responds to an emergency with training, not raw emotion. 'Answer' and 'reply' are narrower: they apply only to verbal or written communication — you answer a question or reply to an email. 'Retort' adds an edge of quickness and sharpness, usually in a disagreement ('a sharp retort'). In everyday use, choose 'react' for spontaneous behaviour, 'respond' for thoughtful action, and 'answer'/'reply' when words are involved.

respond ↗reply ↗answer ↗retort

Common collocations

Nouns

Adverbs

Phrases

  • by + gerund
  • in a + adjective + way

Prepositions

Etymology

LatinEnglish

'React' was formed in the 17th century from the Latin prefix 're-' meaning 'back' or 'again' and the Latin verb 'agere' meaning 'to do' or 'to act'. It originally described a physical force pushing back against another force. By the 19th century it had developed the chemical sense of one substance changing when it meets another, and later broadened to cover any kind of emotional or behavioural response.