English lets you get away with murder when it comes to adverbs and adjectives. Casual speech happily says she sings good, drive safe, come quick — technically wrong, but nobody notices. Portuguese is not so forgiving. The language draws a strict grammatical line between adjectives (which describe nouns and must agree in gender and number) and adverbs (which describe verbs, adjectives, or other adverbs and never change form). Picking the wrong one is not a register issue; it is a grammatical error.
That said, a handful of adverbs and adjectives in Portuguese look identical (rápido, alto, baixo, claro, caro), and the line between "adverbial use of an adjective" and "real adverb" is genuinely fuzzy. This page walks you through the common confusions: the bem/bom and mal/mau pair, adjectives that work adverbially (when and how they stay invariable), and the cases where English reaches for an adverb but Portuguese uses an adjective — or the other way around.
The core rule
- Describing a noun: use an adjective. It agrees with the noun in gender and number.
- Describing a verb, an adjective, or another adverb: use an adverb. It is invariable.
Ela é uma boa cantora.
She's a good singer. (boa = adjective, feminine singular, agrees with cantora)
Ela canta bem.
She sings well. (bem = adverb, invariable)
Os miúdos são muito barulhentos.
The kids are very noisy. (barulhentos = adjective, agrees with miúdos; muito = adverb, invariable)
Put crudely: if you can point at the thing and describe it, reach for the agreeing adjective. If you are describing how the action is done, reach for the invariable adverb.
Bem / Bom and Mal / Mau
These two pairs cause more trouble than any other word in the language for English speakers. English good and bad cover both the adjective and the adverb (she's good, she sings good). Portuguese splits them in two.
| Adjective | Adverb | |
|---|---|---|
| Positive | bom / boa / bons / boas (good) | bem (well) |
| Negative | mau / má / maus / más (bad) | mal (badly) |
O jantar está bom, parabéns ao chef!
The dinner is good, congratulations to the chef!
O chef cozinha bem.
The chef cooks well.
Ele é um mau aluno.
He's a bad student.
Ele estuda mal — nunca faz os trabalhos de casa.
He studies badly — he never does his homework.
The ser / estar + bem vs bom trap
The tricky cases live at the intersection of these adverbs/adjectives and the copulative verbs ser and estar.
Ela é boa.
She is good / good-hearted / morally good. (ser + adjective = permanent trait)
Ela é boa a matemática.
She's good at maths. (permanent ability, adjective)
Ela está bem.
She's well / feeling well / fine. (estar + adverb = temporary state)
Ela está boa.
She looks good / has recovered / (colloquially, and often inappropriately) she's attractive. (estar + adjective)
The estar bem vs estar boa distinction is worth slowing down for. Estar bem is the standard way to say someone is doing well. Estar boa — when used of a person — carries a physical/sexual reading in colloquial speech and is jarring in most social contexts. Used of food or objects, estar bom/boa is totally fine: a sopa está boa (the soup is good — i.e., tastes good right now).
— Como estás? — Estou bem, obrigada!
— How are you? — I'm well, thanks!
A sopa está boa — provaste?
The soup is good (tastes good) — have you tried it?
O doente já está bom.
The patient has recovered / is well again. (estar bom = to have recovered)
Adjectives that can behave as adverbs (invariable)
A specific group of Portuguese adjectives can be used adverbially — that is, placed after a verb to describe how the action is done — and when they do, they stay invariable (do not agree). This overlap with their adjective use is the single most confusing feature of this topic.
The core list:
| Adjective | Adjective use (agrees) | Adverbial use (invariable) |
|---|---|---|
| alto | high, tall, loud (person/thing) | loudly, high (manner) |
| baixo | low, short, quiet (person/thing) | quietly, low (manner) |
| rápido | fast, quick (person/thing) | quickly (manner, casual) |
| devagar | — (used only adverbially) | slowly |
| claro | clear, light-coloured | clearly (manner) |
| caro | expensive | at great cost / expensively |
| barato | cheap | cheaply |
| forte | strong | strongly, loudly, hard |
| direito | straight, right (direction) | straight, directly |
| fundo | deep | deeply |
| longe | — (used only adverbially) | far |
A Maria fala alto.
Maria speaks loudly. (adverbial alto — invariable, no agreement with Maria)
A Maria é alta.
Maria is tall. (adjective alta — feminine singular, agrees with Maria)
Eles falam alto.
They speak loudly. (adverbial alto — stays singular and masculine even with plural subject)
Eles são altos.
They are tall. (adjective altos — agrees in number with eles)
Fala baixo, o bebé está a dormir.
Speak quietly, the baby is sleeping. (adverbial)
A casa é baixa, só tem um andar.
The house is low, it only has one floor. (adjective)
Why does Portuguese allow this?
Historically, these were all adjectives. Over time, certain combinations of verb + adjective (falar alto, correr depressa, pagar caro) crystallised into idiomatic pairs where the adjective functions adverbially. Modern Portuguese preserves the shape of the adjective but treats it grammatically as an invariable adverb.
The parallel -mente form exists (altamente, baixamente, rapidamente, claramente), but it usually carries a different meaning — figurative or abstract rather than literal.
Ele fala alto.
He speaks loudly. (literal, about volume)
É um cientista altamente respeitado.
He's a highly respected scientist. (figurative — means 'to a great degree')
Claramente, há um problema.
Clearly, there is a problem. (sentence adverb — means 'evidently, obviously')
Rápido vs rapidamente vs depressa
A special case. European Portuguese has three ways to say "quickly":
- Depressa — the most natural, most idiomatic PT-PT adverb. Used constantly in speech.
- Rápido — adjective-turned-adverb, colloquial, invariable. Common in speech but less formal.
- Rapidamente — the full -mente adverb. More formal, more written, more abstract.
Vem depressa, o táxi está à espera!
Come quickly, the taxi's waiting! (most natural in speech)
Vem rápido, vamos perder o comboio!
Come quick, we're going to miss the train! (colloquial, invariable)
O polícia interveio rapidamente para controlar a multidão.
The police officer intervened quickly to control the crowd. (formal, written register)
All three are correct. If you are unsure which to use in speech, pick depressa.
Adjectives used as adverbs with ficar and movement verbs
With ficar (to become, to stay) and certain movement verbs, Portuguese uses the agreeing adjective, even though English would use an adverb.
Ela ficou contente com a notícia.
She was happy with the news. (contente is an invariable adjective — same for both genders, but agrees in number)
Eles ficaram contentes com a notícia.
They were happy with the news. (contentes — plural agreement)
Ela chegou cansada da viagem.
She arrived tired from the trip. (cansada — adjective agreeing with ela)
Eles chegaram cansados da viagem.
They arrived tired from the trip. (cansados — agrees with eles)
English speakers often feel pulled to translate "arrived tired" with an adverb like tiredly. Portuguese uses the agreeing adjective because the word describes the state of the subject at arrival, not the manner of arriving.
This is a regular pattern after verbs like chegar, ficar, vir, ir, sair, regressar, voltar, entrar, sair. The adjective describes the state of the subject; the adverb (if there were one) would describe the manner of the action.
Ele saiu zangado da reunião.
He left the meeting angry / angrily. (zangado — the adjective describes his state)
Ele saiu apressadamente da reunião.
He left the meeting hastily. (the adverb describes the manner of leaving)
Both are grammatical — they just say different things. The first tells you his mood; the second tells you how he moved.
English-to-Portuguese mismatches
Some English adverbs do not map onto Portuguese adverbs at all — Portuguese uses an adjective phrase, a noun phrase, or a different construction.
English "work hard" → Portuguese "trabalhar muito" or "trabalhar arduamente"
❌ Trabalho duro todos os dias.
Duro as an adverb is a calque from English 'hard' — uncommon in PT-PT.
✅ Trabalho muito todos os dias. / Trabalho arduamente todos os dias.
I work hard every day.
The English adverbial hard (work hard, study hard, try hard) does not map onto Portuguese duro. You either use muito (a lot) or the -mente form arduamente. Duro can be used adverbially in a narrow set of sporty contexts (o jogo correu duro — the game was tough going), but for general "work hard," use muito or arduamente.
English "sleep well / sleep tight" → "dormir bem"
Dorme bem!
Sleep well! (adverb bem, not the adjective bom)
English "drive safe" → "conduz com cuidado" or "tem cuidado a conduzir"
English drive safe is famously ungrammatical-but-accepted. Portuguese has no equivalent shortcut — you use an adverbial phrase.
❌ Conduz seguro.
Seguro as an adverb (cognate with safe) doesn't work here.
✅ Conduz com cuidado. / Conduz com atenção.
Drive carefully / safely.
English "feel bad" → "sentir-se mal" (not "sentir-se mau")
After sentir-se (to feel), you use the adverb bem or mal, not the adjective bom or mau. This is the biggest single adverb/adjective error English speakers make with Portuguese.
❌ Sinto-me mau por ter faltado ao jantar.
Mau is the adjective 'bad/evil'; the adverb is mal.
✅ Sinto-me mal por ter faltado ao jantar.
I feel bad for missing the dinner.
❌ Ela sente-se boa hoje.
After sentir-se, use the adverb bem.
✅ Ela sente-se bem hoje.
She's feeling well today.
Sentir-se bem and sentir-se mal are fixed expressions meaning "to feel well" and "to feel bad/unwell." The adjective forms bom/boa/mau/má are simply wrong here.
English "taste good / smell good / sound good" → "saber bem / cheirar bem / soar bem"
Verbs of perception in Portuguese take the adverb bem (or mal), not an adjective.
Esta sopa sabe bem.
This soup tastes good.
O café cheira bem.
The coffee smells good.
A ideia soa bem.
The idea sounds good.
This is unusual for English speakers, who are used to tastes good (adjective after a linking verb) rather than tastes well. In Portuguese, saber, cheirar, and soar in these senses are manner verbs, not linking verbs, so they take an adverb.
English "pay dearly / pay a lot" → "pagar caro"
Vais pagar caro por este erro.
You'll pay dearly for this mistake. (caro used adverbially — invariable)
Caro is an adjective (um livro caro — an expensive book), but combines idiomatically with pagar as an invariable adverb meaning "at great cost." Pagar caro is a set expression.
Adverbs that look like adjectives but are not
A few Portuguese words are only adverbs, even though they end in a way that looks adjectival.
| Word | Only usage | Meaning |
|---|---|---|
| devagar | adverb only | slowly |
| bem | adverb only | well |
| mal | adverb only (also noun "evil") | badly |
| longe | adverb only | far |
| perto | adverb only | near |
| cedo | adverb only | early |
| tarde | adverb only (also noun "afternoon") | late |
| assim | adverb only | thus, like this |
| depressa | adverb only | quickly |
Fala devagar, por favor.
Speak slowly, please.
Cheguei tarde a casa.
I got home late.
A cidade fica longe daqui.
The city is far from here.
You cannot agree these words with a noun. ❌ uma pessoa devagara does not exist; if you need the adjective, it is lenta (slow).
Deciding in practice — a worked example
Suppose you want to say She drives very carefully and arrives home tired every night. Let's walk through each modifier.
- very carefully — modifies drive (a verb): adverb needed. PT-PT preference: com muito cuidado (prepositional phrase). Alternative: muito cuidadosamente.
- tired — describes the state of she on arrival (after chegar): agreeing adjective. cansada.
- every night — time expression: adverbial phrase. todas as noites.
Ela conduz com muito cuidado e chega cansada a casa todas as noites.
She drives very carefully and arrives home tired every night.
If you had used cansadamente instead of cansada, you would be saying arrives home tiredly — a different idea (she performs the action of arriving in a tired manner), and one that is marked and unusual in Portuguese. Chega cansada is the natural reading: she arrives, and she is tired.
Common mistakes
❌ Sinto-me mau hoje.
After sentir-se, use the adverb mal, not the adjective mau.
✅ Sinto-me mal hoje.
I feel unwell today.
❌ Esta sopa sabe boa.
Perception verbs like saber take the adverb bem, not the adjective.
✅ Esta sopa sabe bem.
This soup tastes good.
❌ Eles falam altos.
When alto functions as an adverb (about volume), it is invariable.
✅ Eles falam alto.
They speak loudly.
❌ Ela chegou cansadamente.
State of the subject after chegar takes the agreeing adjective.
✅ Ela chegou cansada.
She arrived tired.
❌ Trabalho duro todos os dias.
Duro is not used adverbially in PT-PT for 'hard work.'
✅ Trabalho muito todos os dias. / Trabalho arduamente todos os dias.
I work hard every day.
❌ Ela está boa, obrigada!
Estar boa of a person has a physical/sexual reading; use estar bem for 'feeling well.'
✅ Ela está bem, obrigada!
She's well, thanks!
❌ Conduz seguramente.
Not 'safely' in this sense — seguramente means 'certainly' in PT-PT.
✅ Conduz com cuidado. / Conduz com atenção.
Drive carefully.
Key takeaways
- Adjectives agree with nouns in gender and number. Adverbs are invariable.
- The pairs bem / bom and mal / mau are the highest-frequency split. Ela é boa (adjective) vs ela canta bem (adverb).
- After ser, use the adjective (ser bom — to be good as a permanent trait). After estar, use either the adjective (estar bom — recovered, tasting good) or the adverb (estar bem — feeling well). For "how are you?" answers, always estou bem.
- Some adjectives (alto, baixo, rápido, claro, caro) are used adverbially and stay invariable in that role: falam alto, paga caro.
- The -mente form of these same words usually carries a more abstract or figurative meaning: altamente respeitado (highly respected) vs falar alto (to speak loudly).
- After sentir-se, saber (to taste), cheirar (to smell), soar (to sound), Portuguese uses the adverb (bem / mal), not the adjective.
- After chegar, ficar, sair and similar verbs, Portuguese uses an agreeing adjective to describe the state of the subject: chegou cansada (she arrived tired).
- English hard (work hard) does not translate as duro; use muito or arduamente.
- When in doubt between three words for "quickly," the PT-PT default is depressa.
Related Topics
- Adverbs OverviewA2 — Introduction to Portuguese adverbs — what they are, the main semantic classes, how they are formed, and how European Portuguese adverbs differ from their English equivalents.
- Forming Adverbs with -menteA2 — How to build manner adverbs from adjectives in Portuguese — the feminine-adjective rule, accent loss, the list trick, and the -mente words that do not mean what you think.
- Adverbs of MannerA2 — How things are done in Portuguese — bem, mal, assim, devagar, depressa, the -mente family, and the prepositional phrases that do most of the heavy lifting in everyday PT-PT speech.
- Adjectives OverviewA1 — How adjectives work in European Portuguese: agreement, placement, types, comparison, and invariable forms.
- Adjective Gender AgreementA1 — How Portuguese adjectives change to agree with masculine and feminine nouns, plus the common irregular patterns.