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A2 verb 12 min read

reagir

Practice it Examples Notes & Tips reagir in 30 Seconds

Explanation reagir in your Level:

At the A1 level, you should focus on the most basic meaning of 'reagir', which is 'to react'. Think of it as what happens immediately after something else happens. For example, if you see a friend, you might react by smiling. At this stage, you don't need to worry about complex grammar. Just remember that 'reagir' is an '-ir' verb. In simple sentences, you can use it to describe feelings or basic actions. A common sentence might be 'Eu reajo bem' (I react well) or 'Ele não reage' (He doesn't react). It is important to start noticing the preposition 'a' that often follows the verb, although at A1, simple subject-verb-adverb patterns are more common. Focus on the present tense and the idea of a simple response to a simple action. You might hear this in basic stories or when people talk about their immediate feelings. It is a useful word for describing how you feel about something that just happened. Don't worry about the spelling change in 'reajo' just yet; focus on the infinitive 'reagir' and the third-person 'reage'. This will give you a solid foundation for more complex uses later on.

At the A2 level, you begin to use 'reagir' in more varied contexts, such as describing past events or giving simple advice. You should start to master the preposition 'a' (to), which is crucial for connecting the reaction to the cause. For example, 'reagir ao frio' (reacting to the cold). You will also encounter the first person singular present tense form, 'reajo', and should learn that the 'g' changes to 'j' to keep the sound correct. This is a common pattern in Portuguese verbs ending in '-gir'. At this level, you can describe how you reacted to news, a movie, or a surprise. You might say, 'Eu reagi mal à notícia' (I reacted poorly to the news). You are also starting to use the past tense (Pretérito Perfeito), so knowing that it follows the regular '-ir' pattern (reagi, reagiste, reagiu) is important. You will see this verb in everyday conversations about social interactions and personal feelings. It's a great word for adding detail to your stories about what happened during your day. Practice combining 'reagir' with common adverbs like 'mal', 'bem', 'rápido', and 'devagar'.

At the B1 level, you should be comfortable using 'reagir' across all major tenses, including the future and the conditional. You also start to use the subjunctive mood to express desires or hypothetical situations involving reactions. For example, 'Espero que ela reaja bem' (I hope she reacts well). Your understanding of the word expands to include more abstract concepts, like how a market reacts to news or how a chemical reacts in an experiment. You are now expected to use the preposition 'a' correctly with contractions (ao, à, aos, às). You might also start using the noun form, 'reação', in conjunction with the verb. At B1, you can participate in discussions about social issues and describe how different groups might 'reagir' to a new law or social change. This level requires a more nuanced understanding of the difference between 'reagir' and 'responder', recognizing that 'reagir' is often more visceral or physical. You should also be able to use the imperative form 'reaja!' to encourage someone to take action. Practice using the verb in more complex sentence structures with conjunctions like 'porque' or 'embora'.

At the B2 level, you use 'reagir' with greater precision and in more formal contexts. You understand the nuances of the verb in professional, academic, and literary settings. You can describe complex psychological reactions or detailed scientific processes. For instance, you might discuss how a character in a book 'reage' to an internal conflict. You are also proficient in using 'reagir' in the passive voice or with impersonal 'se' (e.g., 'reage-se de forma diferente em cada cultura'). At this stage, you should be familiar with related terms like 'retroagir' (to act retroactively) and 'interagir' (to interact). You can use 'reagir' to talk about strategy, such as how a business should 'reagir' to a competitor's move. Your vocabulary includes various adverbs that modify the verb, such as 'intempestivamente' (unseasonably/impulsively) or 'ponderadamente' (thoughtfully). You are also able to identify the word in formal news reports and understand the subtle implications of the speaker's choice of 'reagir' over other verbs. This level involves a high degree of grammatical accuracy and the ability to use the verb in sophisticated arguments.

At the C1 level, your use of 'reagir' is near-native. You can use the verb in highly nuanced ways, including metaphorical and idiomatic expressions. You understand the historical and cultural weight the word might carry in different Lusophone countries. For example, you might analyze a political speech where 'reagir' is used as a call to resistance or social mobilization. You are comfortable using the verb in complex hypothetical sentences and in formal academic writing. You can distinguish between 'reagir a' and 'reagir contra', understanding that the latter implies a more active opposition or protest. Your command of the subjunctive and other complex tenses allows you to express subtle shades of meaning, such as 'Se tivéssemos reagido a tempo, o resultado seria outro' (If we had reacted in time, the result would be different). You also recognize the word in technical jargon across various fields, from chemistry to law to psychology. At this level, you can engage in deep discussions about human behavior and the various ways people 'reagem' to systemic issues, using the verb as a central point of your analysis. You exhibit full control over the spelling and pronunciation nuances.

At the C2 level, you have a complete and effortless command of 'reagir'. You use it with the same flexibility and stylistic flair as a highly educated native speaker. You can employ the verb in creative writing, poetry, or high-level philosophical discourse. You are aware of rare or archaic uses of the word and can understand it in any regional dialect of Portuguese. You can play with the word's meaning in puns or wordplay and use it to convey complex emotional states that go beyond a simple response. Your understanding includes the etymological roots of the word and how it relates to other Romance languages. You can lead seminars or give presentations where 'reagir' is a key concept, explaining its implications in sociology, biology, or political science with ease. At this level, the distinction between 'reagir' and its synonyms is second nature, and you always choose the word that provides the exact connotation required by the context. You are also able to correct others' subtle misuses of the verb and explain the grammatical and semantic reasons behind the correction. Your use of 'reagir' is a testament to your total immersion in the Portuguese language.

Practice it Examples Notes & Tips

reagir in 30 Seconds

The Portuguese verb 'reagir' translates to 'to react' and is used to describe responses to physical, emotional, or social stimuli in various daily contexts.
It is a regular '-ir' verb, but requires a spelling change from 'g' to 'j' in the first person singular present tense (reajo) for pronunciation.
Commonly followed by the preposition 'a', it connects a subject's response to a specific cause, such as 'reagir a uma notícia' or 'reagir ao frio'.
This versatile verb is essential for discussing everything from medical symptoms and chemical reactions to political movements and social media interactions.

The Portuguese verb reagir is a multifaceted term that primarily translates to "to react" or "to respond" in English. At its core, it describes the process of acting in response to an external stimulus, whether that stimulus is physical, emotional, social, or even chemical. In everyday Portuguese, you will encounter this word in a vast array of contexts, ranging from a simple physical reflex to complex political movements. Understanding reagir requires an appreciation for its dynamic nature; it is not just about a passive response but often implies an active, sometimes defensive or corrective, counter-action. Whether you are discussing how a patient responds to medication or how a crowd reacts to a provocative speech, reagir is the linguistic bridge between the cause and the effect.

Physical Reflexes: When your body moves automatically in response to pain or surprise, you are reacting. For example, pulling your hand away from a hot stove is a way to reagir instantly to danger.

O paciente começou a reagir aos estímulos sonoros após a cirurgia.

In emotional and social spheres, reagir captures the human element of interaction. If someone insults you, how you reagir defines the subsequent social dynamic. Do you stay calm, or do you become angry? This verb is essential for describing personality traits as well; some people are known to reagir impulsively, while others take time to process information before showing any response. In the modern digital age, the word has taken on a specific technical meaning related to social media, where users "react" to posts with emojis or comments, often referred to as reagir a uma publicação.

Chemical and Biological Context: In a laboratory setting, substances reagir with one another to form new compounds. This scientific usage is identical to the English counterpart, emphasizing the predictable nature of certain interactions.

O ácido vai reagir com a base para produzir sal e água.

Furthermore, reagir is frequently used in political and activist discourse. It implies standing up against injustice or opposing a new law. To reagir contra a opressão is a powerful sentiment in Lusophone history, representing the collective will to change a situation rather than accepting it passively. This nuance of resistance is a key component of the word's weight in formal speeches and historical texts. It suggests that the reaction is not just a side effect, but a conscious choice to alter the course of events.

Economic and Market Trends: Financial news often reports on how the stock markets reagir to interest rate changes or global events. A positive reaction usually means prices go up, while a negative one indicates a decline.

Os mercados costumam reagir com cautela a notícias políticas inesperadas.

In summary, reagir is a versatile verb that covers everything from biological instincts to complex socio-economic responses. Its usage is consistent across Portuguese-speaking countries, making it a fundamental part of the vocabulary for any learner aiming for fluency. Whether you are describing a personal feeling or a global phenomenon, reagir provides the necessary action to describe the interplay between actions and their consequences in the world.

Using reagir correctly in Portuguese involves understanding its conjugation as a regular -ir verb and its syntactic requirement for the preposition a. Because it is a verb of response, it establishes a directional relationship between the subject and the stimulus. In the present tense, the first person singular undergoes a slight spelling change to maintain the soft 'j' sound, becoming eu reajo. This is a common pattern for verbs ending in -gir. Let's explore how this verb functions across different grammatical structures and contexts to ensure you can use it naturally.

Direct Response to Stimuli: The most common structure is [Subject] + [reagir] + [a] + [Noun]. This indicates what the subject is responding to.

Ela não soube como reagir à surpresa que os amigos prepararam.

When talking about the speed or manner of a reaction, adverbs are frequently employed. You might reagir rapidamente (react quickly), reagir mal (react poorly), or reagir com calma (react calmly). These modifiers help clarify the nature of the response. In medical contexts, we often see the verb used to describe how a body part or a condition responds to treatment. For instance, a doctor might say that a tumor is reagindo bem to chemotherapy, meaning it is shrinking or responding as hoped. This metaphorical extension of the word is very common in professional fields.

Adverbial Modifiers: Using adverbs like 'instintivamente' or 'negativamente' provides depth to the action of reacting.

O motorista teve que reagir instintivamente para evitar o acidente na rodovia.

Another important aspect is the use of reagir in the negative. Saying someone não reagiu can imply shock, paralysis, or indifference. It is a powerful way to describe a lack of movement or emotion in a situation where one would normally expect a response. In legal or formal contexts, reagir can also mean to take legal action or to counter a claim. For example, a company might reagir legalmente against a competitor's false accusations. Here, the reaction is a structured, formal process rather than a spontaneous one.

Formal and Legal Usage: In these settings, the verb often implies a counter-offensive or a defense against an action taken by another party.

A empresa decidiu reagir judicialmente contra as calúnias publicadas no jornal.

Finally, consider the imperative form. In a crisis, someone might shout "Reaja!" (React! / Do something!). This is a common way to urge someone to snap out of a daze or to take action in a critical moment. Whether you are using it in a literal sense (a chemical reaction) or a figurative one (responding to a joke), the structure remains consistent. By mastering these patterns, you will find reagir to be an indispensable tool for expressing how people and things interact with their environment in Portuguese.

You will hear reagir across a wide spectrum of daily life in Portuguese-speaking cultures. From the high-stakes environment of a hospital emergency room to the casual banter of a group of friends watching a football match, the word is ubiquitous. Its versatility makes it a staple of news broadcasts, scientific journals, and social media commentary. Understanding where and how it is used in the real world will help you recognize its nuances and use it more effectively in your own conversations.

News and Current Affairs: Journalists frequently use the word to describe public response to government policies, international incidents, or economic shifts.

A população começou a reagir contra o aumento dos preços dos combustíveis.

In the world of sports, commentators use reagir to describe a team's comeback. If a football team is losing by two goals but suddenly starts playing with more intensity and scores, the commentator will say they are reagindo. This usage conveys a sense of renewed energy and a refusal to accept defeat. It is a very common way to describe momentum shifts in any competitive environment. Similarly, in social settings, if a friend tells a shocking story, you might be asked, "Como é que tu reagiste?" (How did you react?), inviting you to share your emotional or verbal response to the news.

Social Media and Pop Culture: The rise of "reaction videos" has made the term even more common among younger generations. YouTubers often title their videos "Reagindo a..." followed by the content they are watching.

Hoje vamos reagir ao novo videoclipe da Anitta.

In medical and scientific contexts, reagir is the standard term for biological responses. You might hear a doctor discuss how a patient's body might reagir to a new medication or an allergen. This usage is precise and technical, often appearing in medical reports and health-related news articles. Furthermore, in psychological contexts, therapists discuss how individuals reagir to trauma or stress, emphasizing the internal mechanisms of coping and response. This broad range of application—from the triviality of a social media click to the gravity of a medical diagnosis—highlights the word's essential role in the Portuguese language.

Daily Life and Relationships: In personal relationships, people often discuss how to reagir to conflict or unexpected news, focusing on emotional intelligence and communication.

É importante pensar antes de reagir a uma mensagem agressiva.

Whether you are reading a newspaper in Lisbon, watching a Brazilian telenovela, or following an Angolan influencer, reagir will appear constantly. It is one of those foundational verbs that allows speakers to articulate the dynamic interplay between people, objects, and ideas. By paying attention to these different contexts, you will gain a deeper understanding of how Portuguese speakers perceive and describe interaction in their world.

While reagir is a relatively straightforward verb, English speakers often stumble on a few specific areas. These mistakes usually stem from direct translation from English or from common pitfalls in Portuguese regular verb conjugation. By being aware of these issues, you can avoid the most common errors and speak more like a native. Let's look at the three primary areas where learners tend to go wrong: the choice of preposition, the spelling in the first person singular, and the confusion between 'reagir' and 'responder'.

The Preposition Trap: In English, we often say "react to something." In Portuguese, the preposition a is mandatory. Many learners forget this and try to use the verb without a preposition or with the wrong one, like com or para.

Errado: Eu não reagi o comentário.
Correto: Eu não reagi ao comentário.

Another frequent mistake occurs during conjugation. Verbs ending in -gir change the g to a j when the following vowel is a or o. This is done to preserve the soft 'zh' sound (like the 's' in 'pleasure'). If you write reago with a g, it would technically be pronounced 're-ah-go' (with a hard 'g' like 'goat'), which is incorrect. Therefore, the first person singular of the present indicative must be written as reajo. This rule also applies to the present subjunctive: que eu reaja, que tu reajas, etc. Forgetting this spelling change is a hallmark of a beginner learner.

Spelling in Conjugation: The g to j shift is essential for phonological consistency. Without it, the word's sound changes completely.

É importante que ele reaja (not reaga) rapidamente à situação.

Finally, there is the subtle distinction between reagir and responder. While they are often interchangeable, responder is more focused on the verbal or written answer, whereas reagir is broader, encompassing physical actions, emotional shifts, and reflexes. If you ask someone a question, they respondem. If you surprise someone with a gift, they reagem with joy. Using reagir when you specifically mean 'to answer a question' can sound a bit dramatic or unnatural in casual conversation. Understanding this nuance will help you choose the most appropriate verb for the situation.

Reagir vs. Responder: Responder is specific to communication; reagir is a broader category of response that includes physical and emotional states.

Ele respondeu à pergunta, mas não reagiu à notícia triste.

By keeping these three points in mind—prepositional use, spelling in specific conjugations, and the semantic difference from 'responder'—you will significantly improve your accuracy. Practice using reajo and reaja in sentences to build muscle memory for the spelling change, and always pause to ensure you've included the necessary a before your object of reaction.

In Portuguese, as in English, there are several synonyms and related terms that can be used instead of reagir, depending on the specific nuance you want to convey. Exploring these alternatives will help you expand your vocabulary and allow for more precise expression. Some words emphasize the speed of the response, while others focus on the corrective or defensive nature of the action. Let's examine some of the most common alternatives and how they compare to the standard use of reagir.

Responder: As discussed previously, responder is the most common synonym. It is best used for verbal, written, or formal replies. It is less about physical reflex and more about intentional communication.

O governo precisa responder às críticas da oposição de forma clara.

Another useful verb is retaliar. This is a much stronger term than reagir and specifically implies a counter-attack or a response meant to cause harm or seek revenge. While you might reagir to an insult by walking away, you would retaliar by insulting the person back. It is often used in political or military contexts to describe a cycle of aggression. Similarly, contra-atacar (to counter-attack) is used in sports or combat to describe a reaction that is specifically designed to overcome the initial aggressor.

Retaliar vs. Reagir: Reagir is neutral; retaliar is aggressive and implies a desire for payback or vengeance.

O exército decidiu retaliar após a invasão da fronteira.

For a more passive or automated response, you might see the verb retroagir. This is more technical and often used in legal contexts to describe a law that applies to events in the past (to act retroactively). It is a specialized form of reaction. On the other hand, atuar (to act) or proceder (to proceed) can sometimes replace reagir when the emphasis is on the action taken rather than the fact that it was a response. For example, "Como devemos proceder nesta situação?" (How should we proceed/react in this situation?).

Atuar and Proceder: These verbs focus on the steps taken or the behavior exhibited, often in a more formal or professional capacity.

A polícia deve atuar rapidamente em casos de emergência.

By understanding these distinctions, you can tailor your speech to the exact situation. Whether you need the neutral, all-encompassing reagir, the communicative responder, or the aggressive retaliar, having these options at your disposal will make your Portuguese more sophisticated and accurate. Always consider the intent and the context of the response before choosing your verb.

How Formal Is It?

Fun Fact

Although 'reagir' feels like a modern word because of its use in chemistry and social media, the concept of 'acting back' has been documented in legal and philosophical texts for centuries.

Pronunciation Guide

UK /ʁi.ɐ.ˈʒiɾ/

US /xe.a.ˈʒiχ/

The stress is on the final syllable: re-a-GIR.

Rhymes With

partir dormir sentir pedir abrir sorrir subir fugir

Common Errors

Pronouncing the 'g' as a hard sound like in 'goat'.
Failing to reduce the 'e' in European Portuguese pronunciation.
Putting the stress on the second-to-last syllable (re-A-gir).
Not vibrating the initial 'r' enough in European Portuguese.
Pronouncing the 'j' in 'reajo' like an English 'j' (dzh) instead of a soft 'zh'.

Difficulty Rating

Reading 2/5

The word is very similar to its English cognate, making it easy to recognize in text.

Writing 3/5

The g-to-j spelling change in 'reajo' and 'reaja' requires attention.

Speaking 3/5

Mastering the European Portuguese 'r' and the soft 'zh' sound takes practice.

Listening 2/5

Clear pronunciation usually makes it easy to spot in conversation.

What to Learn Next

Prerequisites

agir ação fazer sentir responder

Learn Next

interagir retroagir reação reativo consequência

Advanced

intempestivamente ponderadamente reacionário contestaçao retaliação

Grammar to Know

Verbs ending in -gir change 'g' to 'j' before 'a' or 'o'.

Eu reajo (Present), que eu reaja (Subjunctive).

The preposition 'a' is required when reacting TO something.

Reagir à (a+a) situação.

Regular -ir verb conjugation in the Pretérito Perfeito.

Eu reagi, tu reagiste, ele reagiu.

Use of the infinitive after modal verbs.

Você deve reagir.

Position of adverbs with 'reagir'.

Ela reage sempre calmamente.

Examples by Level

Eu reago bem.

I react well.

Simple present tense, first person singular.

Ela reage ao sol.

She reacts to the sun.

Third person singular with preposition 'a'.

Nós reagimos rápido.

We react fast.

First person plural, present tense.

Eles não reagem.

They do not react.

Negative form in the present tense.

Você reage à música?

Do you react to the music?

Interrogative sentence with preposition 'à'.

O gato reage ao som.

The cat reacts to the sound.

Noun subject with third person verb.

Eu quero reagir.

I want to react.

Infinitive form after the verb 'querer'.

Reage agora!

React now!

Imperative mood, informal.

Eu reagi mal à notícia ontem.

I reacted badly to the news yesterday.

Pretérito Perfeito (Past Tense).

Como você reagiu ao presente?

How did you react to the gift?

Question in the past tense.

Ela sempre reage com calma.

She always reacts with calmness.

Use of the adverbial phrase 'com calma'.

O corpo reage ao remédio.

The body reacts to the medicine.

Medical context usage.

Nós reagimos à mudança de planos.

We reacted to the change of plans.

Past tense with contraction 'à'.

Eles reagiram muito rápido ao perigo.

They reacted very quickly to the danger.

Third person plural past tense.

Você precisa reagir à situação.

You need to react to the situation.

Modal verb 'precisar' followed by infinitive.

Eu reajo sempre da mesma forma.

I always react the same way.

Present tense with 'reajo' spelling.

Se ele gritar, eu vou reagir.

If he screams, I will react.

Future with 'ir' + infinitive.

Espero que ela reaja bem à surpresa.

I hope she reacts well to the surprise.

Present subjunctive mood.

O mercado reagiu negativamente aos impostos.

The market reacted negatively to the taxes.

Economic context usage.

Nós reagiríamos se tivéssemos tempo.

We would react if we had time.

Conditional mood.

É importante que todos reajam ao problema.

It is important that everyone reacts to the problem.

Subjunctive mood after 'é importante que'.

Eles estão reagindo aos estímulos visuais.

They are reacting to the visual stimuli.

Present continuous tense.

Você reagiria se alguém te insultasse?

Would you react if someone insulted you?

Conditional and imperfect subjunctive.

O filme me fez reagir de forma estranha.

The movie made me react in a strange way.

Causative structure with 'fazer'.

A empresa reagiu prontamente à crise financeira.

The company reacted promptly to the financial crisis.

Formal business context.

Embora tenha ficado chocado, ele não reagiu.

Although he was shocked, he didn't react.

Concessive clause with 'embora'.

Os cientistas observam como as células reagem.

Scientists observe how the cells react.

Scientific context.

Ela reagiu contra as injustiças sociais.

She reacted against social injustices.

Use of 'reagir contra'.

O público reagiu com aplausos entusiasmados.

The audience reacted with enthusiastic applause.

Descriptive adverbial phrase.

Duvido que eles reajam à provocação.

I doubt they will react to the provocation.

Subjunctive after verbs of doubt.

Como o organismo reage a esse tipo de vírus?

How does the organism react to this type of virus?

Biological context.

O governo deve reagir para acalmar a população.

The government must react to calm the population.

Modal 'deve' implying necessity.

O autor reage às críticas literárias no seu novo livro.

The author reacts to literary criticism in his new book.

Literary/Academic context.

É fundamental que a sociedade reaja ao retrocesso.

It is fundamental that society reacts to the regression.

Sophisticated social commentary.

Caso o paciente não reaja, mudaremos a dosagem.

In case the patient does not react, we will change the dosage.

Conditional 'caso' with subjunctive.

Ele costuma reagir intempestivamente a qualquer crítica.

He usually reacts impulsively to any criticism.

Use of the advanced adverb 'intempestivamente'.

A bolsa de valores reagiu com volatilidade aos dados.

The stock exchange reacted with volatility to the data.

Specific economic terminology.

Reagir à altura é a única forma de ser respeitado.

Reacting in kind is the only way to be respected.

Idiomatic expression 'reagir à altura'.

Não se pode prever como a massa irá reagir.

One cannot predict how the masses will react.

Impersonal 'se' and sociological context.

Ela reage com uma ironia fina a insultos grosseiros.

She reacts with subtle irony to coarse insults.

Nuanced description of behavior.

A obra reage aos paradigmas estéticos do século XIX.

The work reacts to the aesthetic paradigms of the 19th century.

High-level art criticism.

Oxalá o país reaja antes que seja tarde demais.

Would that the country reacts before it is too late.

Use of the archaic/formal 'oxalá'.

Sua incapacidade de reagir denota uma apatia profunda.

His inability to react denotes a profound apathy.

Complex psychological analysis.

O sistema imunológico reage de forma orquestrada.

The immune system reacts in an orchestrated manner.

Advanced biological description.

Reagimos ao mundo através do prisma da nossa cultura.

We react to the world through the prism of our culture.

Philosophical statement.

A matéria reage sob condições extremas de pressão.

Matter reacts under extreme pressure conditions.

Advanced physics context.

É imperativo que as instituições reajam ao autoritarismo.

It is imperative that institutions react to authoritarianism.

Formal political discourse.

Ele reage aos estímulos com uma precisão cirúrgica.

He reacts to stimuli with surgical precision.

Metaphorical use of 'cirúrgica'.

Common Collocations

reagir mal

reagir bem

reagir a tempo

reagir prontamente

reagir instintivamente

reagir com violência

reagir negativamente

reagir positivamente

reagir contra

reagir em silêncio

Common Phrases

Como reagiste?

— A standard question asking for someone's response to an event. It is used in casual conversation.

Como reagiste quando soubeste que ganhaste o prémio?

Não saber como reagir

— Expresses confusion or shock where a person is unsure of the appropriate response. Very common in emotional stories.

Fiquei tão surpreso que não soube como reagir.

Reagir à altura

— To respond in a way that matches the intensity or nature of the original action, often implying a strong defense.

Se ele for rude, eu vou reagir à altura.

Reagir a estímulos

— A technical phrase used in medicine and psychology to describe basic responses. It is used for both humans and animals.

O recém-nascido já começa a reagir a estímulos sonoros.

Reagir em cadeia

— To react in a way that triggers further reactions, similar to a domino effect. Used in science and sociology.

O acidente causou uma série de eventos que reagiram em cadeia.

Reagir por impulso

— To act without thinking first. It describes spontaneous and often regrettable responses.

Tento não reagir por impulso quando estou zangado.

Reagir com frieza

— To respond without showing any emotion, often used to describe someone who is very controlled or detached.

Ela reagiu com frieza ao anúncio do divórcio.

Reagir ao mercado

— A business term meaning to adjust strategies based on current economic trends or competitor actions.

As empresas precisam de reagir ao mercado para sobreviver.

Reagir a uma provocação

— To respond to someone who is trying to make you angry or upset. Often used in advice.

O melhor é nunca reagir a uma provocação barata.

Reagir a tempo e horas

— An idiomatic way of saying someone reacted exactly when they needed to, without delay.

Felizmente, os bombeiros reagiram a tempo e horas.

Often Confused With

reagir vs responder

English speakers often use 'responder' when 'reagir' is more appropriate for physical or emotional responses.

reagir vs agir

Agir means to act; reagir means to act in response. Don't forget the 're-' prefix when it's a response.

reagir vs regredir

Sounds similar but means to regress or go backwards. Be careful with the vowels.

Idioms & Expressions

"Reagir como um bicho"

— To react in a very aggressive or wild way, losing one's civilized composure. It implies a loss of control.

Ele reagiu como um bicho quando lhe tiraram o telemóvel.

informal

"Reagir de cabeça quente"

— To react while angry, often leading to poor decisions or saying things one might regret later.

Não deves reagir de cabeça quente; espera até amanhã.

informal

"Reagir com unhas e dentes"

— To fight back or react with everything you have, showing great determination and strength.

A comunidade reagiu com unhas e dentes contra o fecho da escola.

neutral

"Reagir a seco"

— To react in a blunt, direct, and unemotional way, often perceived as being rude or overly brief.

Ele reagiu a seco, dizendo apenas que não concordava.

neutral

"Reagir por instinto de sobrevivência"

— To react based on the primal need to stay safe or alive, often used to justify extreme actions.

No meio do pânico, todos reagiram por instinto de sobrevivência.

neutral

"Reagir como se nada fosse"

— To react as if something important or shocking is actually trivial or unimportant. It shows great composure.

Apesar do insulto, ela reagiu como se nada fosse.

neutral

"Reagir à primeira"

— To react immediately at the first sign or the first attempt, showing high sensitivity or readiness.

O motor reagiu à primeira quando rodei a chave.

informal

"Reagir com o estômago"

— To react based on visceral feelings or gut instinct rather than logical thought. Similar to 'reagir por impulso'.

Muitos eleitores reagem com o estômago em vez de lerem os programas.

informal

"Reagir para não chorar"

— A phrase used when something is so bad or ridiculous that the person reacts with humor or irony just to cope.

Só me resta reagir com piadas para não chorar com esta situação.

informal

"Reagir em legítima defesa"

— A legal and common phrase meaning to react in order to protect oneself from an immediate threat.

O tribunal considerou que ele reagiu em legítima defesa.

formal

Easily Confused

reagir vs reagente

Looks like an adjective but is often a noun.

Reagente is the substance that causes a reaction in chemistry, while reagir is the verb.

Adicionamos o reagente para ver como a mistura ia reagir.

reagir vs reacionário

Comes from the same root but has a specific political meaning.

A 'reacionário' is someone who opposes social or political progress (a reactionary).

Ele tem ideias reacionárias e não quer mudar nada.

reagir vs retroagir

Very similar spelling and sound.

Retroagir is specifically about acting backwards in time (retroactively).

A lei não pode retroagir para punir atos passados.

reagir vs interagir

Also describes interaction.

Interagir is a two-way process (interact), while reagir is a one-way response to a stimulus.

As crianças precisam de interagir umas com as outras.

reagir vs redigir

Ends in -igir and sounds similar.

Redigir means to write or to draft a document.

Vou redigir o contrato agora mesmo.

Sentence Patterns

[Subject] + reage + bem/mal.

O menino reage bem.

[Subject] + reagiu + ao/à + [Noun].

Ela reagiu à surpresa.

Espero que + [Subject] + reaja + [Adverb].

Espero que ele reaja rápido.

[Subject] + reagiu + contra + [Noun].

Eles reagiram contra o governo.

[Subject] + costuma + reagir + [Advanced Adverb] + a.

Ela costuma reagir intempestivamente a críticas.

A incapacidade de + reagir + denota + [Noun].

A incapacidade de reagir denota apatia.

Se + [Subject] + [Subjunctive], + [Subject] + reagiria.

Se ele soubesse, ele reagiria.

Como é que + [Subject] + reagiu?

Como é que tu reagiste?

Word Family

Nouns

reação (reaction)

reatividade (reactivity)

reagente (reagent)

reator (reactor)

Verbs

reagir (to react)

retroagir (to act retroactively)

interagir (to interact)

Adjectives

reativo (reactive)

reacionário (reactionary)

reagente (reacting/reagent)

ação (action)

agente (agent)

agir (to act)

atuação (performance/action)

interação (interaction)

How to Use It

frequency

Very high; it is a top 500 verb in Portuguese.

Common Mistakes

Eu reago (with a 'g'). → Eu reajo.
You must change 'g' to 'j' before 'o' to maintain the soft 'zh' sound.
Reagir o comentário. → Reagir ao comentário.
The verb 'reagir' requires the preposition 'a' when followed by a noun.
Ele reaga bem. → Ele reage bem.
The present tense third person singular for -ir verbs ends in -e, not -a (unless it's subjunctive).
Eu respondi ao presente. → Eu reagi ao presente.
While 'respondi' is okay, 'reagi' is much more natural for a physical/emotional response to a gift.
A lei vai reagir ao passado. → A lei vai retroagir ao passado.
In legal contexts, 'retroagir' is the specific term for acting on past events.

Tips

Watch the Contractions

Since 'reagir' takes the preposition 'a', you will almost always see it combined with articles. 'A + o = ao', 'a + a = à', 'a + os = aos', 'a + as = às'. Master these to sound natural.

Use it for Social Media

If you want to talk about Facebook or Instagram in Portuguese, 'reagir' is the word for clicking those emoji buttons. 'Ele reagiu com um coração'.

Soft G and J

Ensure the 'g' in 'reage' and the 'j' in 'reajo' are soft. Think of the sound in 'vision' or 'measure'. Never use a hard 'dzh' sound like in 'jump'.

Reagir vs Responder

If you are replying to a text, use 'responder'. If you are crying because of a text, use 'reagir'. One is the communication, the other is the emotional/physical effect.

Adverbs Matter

Because 'reagir' is a general verb, adding an adverb like 'mal', 'bem', 'prontamente', or 'negativamente' is essential to give the sentence meaning.

Brazilian Slang

In Brazil, 'Reage!' is a common motivational slang. It's like saying 'Snap out of it!' or 'Get it together!'.

Scientific Context

In science papers, 'reagir' is used to describe how variables change in response to others. It's a very precise and respected word in academia.

The 'Re-' Prefix

Remember that 're-' often means 'back'. Re-agir is to act back. This helps distinguish it from 'agir' (to act).

Avoid 'Reagar'

Some learners try to make the verb 'reagar' because of the 'g'. This verb does not exist. It is always 'reagir'.

Stress the End

Always put the stress on the last syllable: re-a-GIR. In Portuguese, infinitives ending in -r are almost always stressed on the final syllable.

Memorize It

Mnemonic

Think of a RE-al AG-ent. An agent acts; a RE-AG-ir acts BACK (re-) when something happens. RE-AG-IR = RE-ACT.

Visual Association

Imagine a tennis player hitting a ball back. The ball coming at them is the stimulus, and their swing is the 'reagir'.

Word Web

ação estímulo resposta reflexo química sentimento movimento defesa

Challenge

Try to write three sentences using 'reagir': one about a physical reflex, one about a social media post, and one about a political event.

Word Origin

The word 'reagir' comes from the Medieval Latin 'reagere'. It is composed of the prefix 're-' (meaning back or again) and the verb 'agere' (meaning to act or to do). This literally translates to 'to act back'.

Original meaning: The original meaning was to perform an action in response to another action, which remains the core definition today.

It belongs to the Romance language family, derived from Latin, and has cognates in French (réagir), Spanish (reaccionar), and Italian (reagire).

Cultural Context

Be careful when telling someone to 'reagir' in a traumatic situation, as it can sound dismissive of their shock or pain. In these cases, 'O que posso fazer?' is better.

English speakers might use 'respond' more often than 'react' in formal settings, whereas in Portuguese, 'reagir' is quite common in both formal and informal contexts.

The phrase 'Reage, mulher, bota um cropped' became a massive viral meme in Brazil, used to encourage women to feel confident after a breakup. Newton's Third Law (Action and Reaction) is translated as 'Lei da Ação e Reação' in Portuguese textbooks. Numerous Portuguese fado songs talk about 'reagir ao destino' (reacting to destiny).

Practice in Real Life

Real-World Contexts

Health and Medicine

reagir ao tratamento
reagir à anestesia
reagir a um alergénio
não reagir a estímulos

Social Situations

reagir a uma piada
reagir a um insulto
reagir com surpresa
reagir por vergonha

Business and Economy

reagir à concorrência
reagir à queda das ações
reagir às exigências do mercado
reagir prontamente a crises

Science and Chemistry

reagir com oxigénio
reagir sob pressão
velocidade de reagir
substância que reage

Politics and Law

reagir contra a lei
reagir judicialmente
reagir a um ataque
reagir à altura

Conversation Starters

"Como você costuma reagir quando recebe uma notícia inesperada?"

"Você acha que as pessoas reagem de forma diferente nas redes sociais do que na vida real?"

"Qual foi a coisa mais estranha a que você já viu alguém reagir?"

"Como os mercados do seu país reagem a mudanças políticas?"

"Você prefere pensar muito antes de reagir ou reage por instinto?"

Journal Prompts

Descreve uma situação em que reagiste de uma forma de que te arrependeste mais tarde.

Como é que o teu corpo reage ao stress e ao cansaço?

Escreve sobre uma figura histórica que reagiu com coragem contra uma injustiça.

Reflete sobre a forma como costumas reagir a críticas no teu trabalho ou estudos.

Imagina um mundo onde ninguém consegue reagir a nada. Como seria a vida?

Frequently Asked Questions

10 questions

Not always, but in about 90% of cases where a cause is mentioned, 'a' is used. For example, 'reagir ao frio'. However, you can also say 'reagir contra' (react against) or 'reagir com' (react with). If no cause is mentioned, like 'ele não reage', no preposition is needed.

It is 'eu reajo'. You must change the 'g' to a 'j' to keep the soft 'zh' sound. If you used a 'g', it would sound like 're-ah-go', which is wrong. This rule applies to all verbs ending in -gir.

Yes, but it's broader. While 'responder' is specifically for answering questions or letters, 'reagir' is used for any kind of response, including non-verbal ones like a smile, a flinch, or a change in mood.

This is a common social media term in Brazil and Portugal for a 'reaction video' or 'reaction stream' where an influencer watches a video and reacts to it in real-time.

Yes, it follows the standard pattern for -ir verbs: reagi, reagiste, reagiu, reagimos, reagistes, reagiram. There are no irregular shifts in the past tense stems.

It means to respond to something with the same level of intensity or quality. If someone is very professional with you, and you are professional back, you are reacting 'à altura'. It's often used in the context of standing up for oneself.

Absolutely. It's the standard word for animal responses. 'O cão reage ao dono' (The dog reacts to the owner).

'Reagir' is always a response to something else. 'Atuar' simply means to act or to perform. You can 'atuar' without there being a specific stimulus, but you can only 'reagir' if something happened first.

Yes, it's the official term. 'O hidrogénio reage com o oxigénio' (Hydrogen reacts with oxygen).

There isn't a single word that perfectly matches 'overreact'. Usually, we say 'reagir de forma exagerada' or 'exagerar na reação'.