Comuniquei o sinistro pelo aplicativo.

Comuniquei is the first-person singular form of comunicar in the pretérito perfeito (the completed past, often matching the English simple past).

So it means:

• I reported
• I informed
• I notified

In this sentence, comuniquei tells you that the action was completed in the past.

Portuguese often leaves out subject pronouns when the verb form already makes the subject clear.

So:

• Comuniquei o sinistro pelo aplicativo.
• Eu comuniquei o sinistro pelo aplicativo.

Both are correct, and both mean the same thing. The version without eu sounds very natural in Portuguese.

Because comuniquei can only mean I communicated/reported, the subject is understood automatically.

Because comunicar can take a direct object in Portuguese.

That means you can say:

• comunicar algo = to report / inform / notify something
• comunicar algo a alguém = to report / inform / notify something to someone

So:

• Comuniquei o sinistro = I reported the claim/incident

Using do here would not fit this structure.

This is a common thing for English speakers to notice, because verb patterns often do not match exactly between English and Portuguese.

No. In this context, sinistro is an insurance term.

It usually means something like:

• claim
• incident
• loss event
• accident/damage event reported to an insurance company

So in insurance language, sinistro is not the English adjective sinister.

Outside insurance, sinistro can sometimes mean creepy, ominous, or sinister in a different context, but that is not what it means here.

Portuguese uses definite articles more often than English does.

So o sinistro literally means the claim / the incident, but in natural English translation you may or may not use the, depending on context.

Here, o suggests a specific incident/claim that the speaker is referring to—probably one already known in the situation.

This is very normal in Portuguese:

• o carro = the car
• a conta = the bill/account
• o aplicativo = the app

Pelo is a contraction of:

• por + o = pelo

In this sentence, pelo aplicativo means:

• through the app
• via the app
• using the app

So pelo here expresses the means or method used to do the action.

Yes, sometimes, but the nuance is a little different.

• pelo aplicativo = through / by means of the app
• no aplicativo = in / on the app

So:

• Comuniquei o sinistro pelo aplicativo emphasizes the app as the channel or method
• Comuniquei o sinistro no aplicativo emphasizes the action happening inside/on the app

In many real-life situations, both could sound acceptable, but pelo aplicativo is especially natural when you mean I used the app to do it.

Also, no is a contraction of:

• em + o = no

Yes. Aplicativo is the standard full word in Brazilian Portuguese for app/application.

You will also hear:

• app

That is very common in everyday speech, especially in informal contexts.

So these are both natural in Brazil:

• pelo aplicativo
• pelo app

The first sounds a bit more standard/full; the second sounds more casual and modern.

Comuniquei o sinistro pelo aplicativo is a completely natural word order.

It follows a very common pattern:

• verb + object + method

You could change the order for emphasis, for example:

• Pelo aplicativo, comuniquei o sinistro.

But that sounds more marked or stylistically deliberate. The original sentence is the most neutral and natural version.

In Brazilian Portuguese, comuniquei is pronounced approximately like:

• koh-moo-nee-KEI

A few helpful notes:

• qu before e gives a k sound
• the stress falls on the last syllable: -quei
• the ending -ei sounds roughly like ay

So the whole sentence is approximately:

• koh-moo-nee-KEI oo see-NEES-troo PEH-loh ah-plee-kah-CHEE-voh

That is only an approximation, but it can help an English speaker get started.

The base form is comunicar.

Some useful forms are:

• comunicar = to communicate / report / notify
• comunico = I communicate / I report
• comuniquei = I communicated / I reported
• comunicou = he/she/you reported
• comunicado = communicated / notified (past participle in some contexts)

In insurance or formal contexts, comunicar often means to report officially.