The Preposition sem | Portuguese (Portugal) Grammar

The preposition sem is the mirror image of com. Wherever com adds something — a companion, a tool, a quality, an ingredient — sem takes it away. It translates directly as "without," and the two prepositions form a matched pair that you will use constantly. Sem is simpler than com in one important respect: it has no contractions, not with articles and not with personal pronouns. You always write it as a separate word.

The real subtlety with sem shows up in two places. First, it chains naturally with the personal infinitive (a structure English lacks), giving sentences like sem nos darmos conta (without us realising it). Second, it interacts with double negation in ways that surprise English speakers — sem nada (literally "without nothing") is perfectly correct Portuguese for "without anything."

No contractions — ever

Before the semantics, a quick structural rule. Unlike a, de, em, and por, the preposition sem never contracts with anything. Every combination stays as two words:

Combination	Form
sem + o	sem o
sem + a	sem a
sem + os	sem os
sem + as	sem as
sem + mim / ti / ele / nós	sem mim, sem ti, sem ele, sem nós

There is no semo, no sema, no semnós. This makes sem one of the easiest prepositions in Portuguese from a spelling standpoint.

Saí de casa sem o telemóvel e só dei por isso à hora de almoço.

I left the house without my phone and only noticed at lunchtime.

Sem ti isto não era a mesma coisa.

Without you this wouldn't be the same thing.

1. Absence or lack — "without"

The core use: sem marks the thing that is missing from the scene. What in English would be "without X," in Portuguese is always sem X.

Prefiro o café sem açúcar, obrigada.

I prefer coffee without sugar, thanks.

Tens de ir ao dentista, não podes andar sem um dente.

You need to go to the dentist, you can't go around without a tooth.

Um dia sem sol em Lisboa é quase uma ofensa pessoal.

A sunless day in Lisbon is almost a personal insult.

This is the direct mirror of com: if com café means "with coffee," sem café means "without coffee." The pairing works in both directions. Whenever you can use one, you can use the other with the opposite meaning.

Ela chega sempre cedo ao trabalho, com ou sem trânsito.

She always gets to work early, with or without traffic.

2. Negative accompaniment — "without someone"

When sem introduces a person, it means you are going somewhere — or doing something — without their company.

Vim sem o João porque ele estava a acabar um relatório.

I came without João because he was finishing a report.

Não vou à festa sem ti.

I'm not going to the party without you.

Os miúdos foram ao parque sem os pais, já têm idade para isso.

The kids went to the park without their parents, they're old enough now.

Compare the equivalent com sentences and you will see the direct opposition:

Vim com o João porque ele queria conhecer o sítio.

I came with João because he wanted to see the place.

3. Adverbial phrases — manner without

Just as com + noun often does the work of an English adverb ("with care" → carefully), sem + noun frequently expresses the absence of that manner. These expressions are some of the most common fixed phrases in the language.

Portuguese	English
sem dúvida	without a doubt, certainly
sem pressa	without rushing, in no hurry
sem problema	no problem
sem medo	without fear, fearlessly
sem razão	for no reason, unreasonably
sem cuidado	carelessly
sem parar	without stopping
sem mais nem menos	just like that, out of the blue

Podes ficar, sem problema.

You can stay, no problem.

Vamos sem pressa, o comboio só sai daqui a uma hora.

Let's take our time, the train doesn't leave for another hour.

Ele despediu-se sem mais nem menos, nem sequer explicou porquê.

He quit just like that, didn't even explain why.

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Treat these phrases as single vocabulary items. Trying to assemble them from parts (for example, saying sem um problema for no problem) sounds foreign.

4. Sem + infinitive — the personal infinitive trick

Here is where sem does something English cannot. When the missing action would be performed by someone, Portuguese uses sem plus the infinitive of the verb. If the subject of the missing action is the same as the main clause, use the plain infinitive. If the subject is different — or if you want to mark it explicitly — use the personal infinitive.

Plain infinitive (same subject):

Saí de casa sem tomar o pequeno-almoço.

I left the house without having breakfast.

Ela respondeu sem pensar duas vezes.

She answered without thinking twice.

Personal infinitive (subject needs to be made explicit):

Sem nos darmos conta, já eram duas da manhã.

Without us realising it, it was already two in the morning.

Ele entrou na sala sem os pais saberem.

He went into the room without his parents knowing.

Notice how in sem nos darmos conta the verb darmos carries the first-person plural ending -mos, even though it is an infinitive. That is the personal infinitive at work — it encodes the subject directly on the verb. English does not have this structure; the closest equivalent is "without us doing X," which requires a pronoun. Portuguese lets the verb ending do the job.

Podes ficar sem te preocupares com nada.

You can stay without worrying about anything.

Partiram sem se despedirem.

They left without saying goodbye.

See the personal infinitive for a full treatment of this construction.

Why you (usually) don't need sem que + subjunctive

English speakers often try to say "without him knowing" by reaching for a conjunction-plus-subjunctive structure, because that is what the grammar books suggest for clauses after negative conjunctions. In Portuguese, sem que + subjunctive does exist, but it feels heavier than needed for most everyday sentences. The personal infinitive is far more natural.

Entrou sem ele saber.

He came in without him knowing. (natural)

Entrou sem que ele soubesse.

He came in without him knowing. (correct but formal, slightly written)

Both are grammatical. The first — sem + personal infinitive — is the one you will hear in cafés, on the phone, and in everyday writing. Reserve sem que + subjunctive for more formal or literary contexts, or when the structure of the sentence demands a full clause.

5. Conditional "without" — "if not"

Sem can introduce a condition that is treated as a negative prerequisite. It is roughly equivalent to English without -ing meaning if you don't.

Sem estudar, não se aprende.

Without studying, you don't learn.

Sem a ajuda dele, não teria conseguido.

Without his help, I wouldn't have managed it.

Sem água e sem sombra, aquele passeio no verão foi um inferno.

Without water and without shade, that walk in the summer was hell.

This is a stylish, compact way to express an unreal or hypothetical absence — it feels slightly more elegant than a full se + verb clause.

6. Double negation — sem + ninguém, nada, nenhum

Portuguese does not worry about double negatives the way English does. If you say "I left without anyone seeing me," English insists on anyone. Portuguese flips this: because sem is already negative, the following indefinite pronoun appears in its negative form.

Ele saiu sem ninguém dar por isso.

He left without anyone noticing.

Comi sem dizer nada a ninguém.

I ate without saying anything to anyone.

Chegou a Lisboa sem nenhum dinheiro no bolso.

He arrived in Lisbon without any money in his pocket.

Translating these literally into English — "without no one noticing," "without saying nothing to no one," "without no money" — would be ungrammatical in English but is perfectly correct in Portuguese. Both languages use polarity agreement; they just set the threshold at different places.

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The default pattern inside a sem phrase is the negative indefinite: sem nada, sem ninguém, sem nenhum, sem nunca. Using alguma coisa, alguém, algum after sem sounds strange to a native ear.

7. Verbs that prefer sem

A few verbs idiomatically pair with sem in ways English does not telegraph:

Ficaste sem nada depois daquele investimento.

You were left with nothing after that investment.

A empresa está sem dinheiro para pagar os salários este mês.

The company has no money to pay the salaries this month.

Here the construction is ficar sem + noun or estar sem + noun, which covers a semantic range English distributes across "run out of," "be out of," "be left without," "have no."

Sem vs. não ter — a stylistic note

Both estar/ficar sem X and não ter X can translate "to not have X," but they carry different nuances. Sem emphasises the absence as a state, while não ter simply negates possession.

Não tenho tempo para isto agora.

I don't have time for this right now. (neutral)

Estou sem tempo para isto agora.

I'm out of time for this right now. (emphasises the lack)

The second version has a slight ring of complaint or exhaustion — the speaker is flagging the absence, not just stating a fact. Use it when you want that flavour.

Common Mistakes

❌ Saí sem que eu tomasse o pequeno-almoço.

Incorrect — same subject doesn't need sem que + subjunctive.

✅ Saí sem tomar o pequeno-almoço.

I left without having breakfast.

❌ Partiu sem dizer nada a alguém.

Incorrect — after sem, use the negative indefinite ninguém.

✅ Partiu sem dizer nada a ninguém.

He left without saying anything to anyone.

❌ Entrou sem ele sabia.

Incorrect — sem + verb requires the infinitive (here, the personal infinitive), not the indicative.

✅ Entrou sem ele saber.

He came in without him knowing.

❌ Estou sem do meu telemóvel há dois dias.

Incorrect — do not add an extra preposition after sem.

✅ Estou sem o meu telemóvel há dois dias.

I've been without my phone for two days.

❌ Semo dinheiro, não posso ir ao cinema.

Incorrect — sem does not contract with articles.

✅ Sem o dinheiro, não posso ir ao cinema.

Without the money, I can't go to the cinema.

The last error is rare but revealing: learners who have internalised the contraction patterns of por → pelo or em → no sometimes extend the logic to sem. Resist the temptation. Sem never contracts.

Key Takeaways

Sem means "without" and is the direct opposite of com.
It never contracts — with articles, pronouns, or anything else.
Sem + infinitive is the standard way to express without doing X; use the personal infinitive when the subject is different or needs to be explicit.
After sem, Portuguese uses negative indefinites (ninguém, nada, nenhum), not positive ones (alguém, alguma coisa, algum).
Fixed phrases like sem dúvida, sem pressa, sem problema, sem medo are everyday vocabulary — memorise them as units.
Prefer sem + infinitive over sem que + subjunctive in speech; the latter is reserved for more formal contexts.