Ambos chegaram cedo.

Ambos means both.

In Brazilian Portuguese, it is correct, but it can sound a bit more formal or written than everyday speech. In casual spoken Brazilian Portuguese, people often say:

• os dois chegaram cedo = the two / both arrived early
• os dois chegaram cedo is usually more common in conversation than ambos chegaram cedo

So ambos chegaram cedo is perfectly natural, but it has a slightly more formal tone.

Because ambos refers to two people, so the subject is plural.

• ambos = both
• chegaram = they arrived

The singular form would be chegou, but that would not match ambos.

So:

• ambos chegaram = both arrived
• not ambos chegou

Chegaram is in the preterite tense, which is used for a completed action in the past.

The verb is chegar = to arrive

Conjugation here:

• eu cheguei
• você/ele/ela chegou
• nós chegamos
• eles/elas chegaram

So ambos chegaram cedo means that the arrival happened and was completed in the past.

Because cedo is an adverb here. It modifies the verb chegaram and tells us when they arrived.

• cedo = early
• tarde = late

Adverbs do not change for gender or number in Portuguese, so cedo stays the same.

Examples:

• ela chegou cedo
• eles chegaram cedo
• ambas chegaram cedo

In all of these, cedo stays unchanged.

They both mean both, but they agree with the gender of the people or things being referred to.

• ambos = masculine plural
• ambas = feminine plural

Examples:

• ambos chegaram cedo = both of them arrived early, referring to two men or to a mixed group
• ambas chegaram cedo = both of them arrived early, referring to two women

As in many parts of Portuguese grammar, the masculine plural can also be used for a mixed-gender pair.

Yes. In a sentence like ambos chegaram cedo, ambos often naturally corresponds to both or both of them in English.

Portuguese does not need to add a separate word for of them here. The idea is already built into ambos when the context is clear.

If needed, Portuguese can be more explicit:

• ambos eles is generally not the normal way
• more natural would be something like os dois or a fuller phrase depending on context

But in your sentence, ambos alone works perfectly.

No. It can appear in other positions, although sentence-initial position is very common.

Examples:

• ambos chegaram cedo
• ambos os alunos chegaram cedo
• os alunos ambos chegaram cedo — possible, but less common and more formal/literary

In normal Brazilian Portuguese, the most natural patterns are usually:

• ambos chegaram cedo
• ambos os alunos chegaram cedo
• os dois alunos chegaram cedo

Normally, no. That sounds redundant, because both ambos and os dois already express the idea of both.

Use one or the other:

• ambos chegaram cedo
• os dois chegaram cedo

Not:

• ambos os dois chegaram cedo

They usually mean the same thing: both.

The main difference is tone and frequency:

• ambos = more formal, more written, sometimes more concise
• os dois = more common in everyday Brazilian speech

Examples:

• ambos chegaram cedo = correct, slightly more formal
• os dois chegaram cedo = very common and natural in conversation

If you are aiming for natural spoken Brazilian Portuguese, os dois is often the safer everyday choice.

Yes. Ambos and ambas can refer to people or things.

Examples:

• ambos os carros são novos = both cars are new
• ambas as casas foram vendidas = both houses were sold

In your sentence, ambos chegaram cedo, it clearly refers to people, because chegar means to arrive, something people do in this kind of context.

Because ambos can be used by itself as a pronoun, meaning both.

So:

• ambos chegaram cedo = both arrived early

But ambos can also be used before a noun, often with an article:

• ambos os alunos chegaram cedo = both students arrived early
• ambas as meninas chegaram cedo = both girls arrived early

So in your sentence, there is no article because there is no noun after ambos.

A rough pronunciation guide is:

AHM-boos sheh-GAH-rahm SEH-doo

A few notes:

• ambos: the am has a nasal sound
• ch in chegaram sounds like sh
• the stressed syllable in chegaram is ga
• cedo sounds roughly like SEH-do

Pronunciation varies a little by region, but this is a good general Brazilian approximation.

Not usually, if you want the same meaning.

• chegaram = arrived
• vieram = came

Sometimes in English those ideas overlap, but in Portuguese they are different verbs:

• ambos chegaram cedo = both arrived early
• ambos vieram cedo = both came early

The second one focuses more on movement toward a place or speaker, while the first simply states the arrival. In many contexts, chegaram is the more direct choice for arrived.