A reunião é online.

In A reunião é online, the A is the definite article and means the, not a.

• A reunião = the meeting
• If you wanted a meeting, you’d say uma reunião.

So the sentence translates as “The meeting is online.”

Portuguese has two verbs for to be: ser and estar.

• ser (é) is used for more permanent / defining characteristics or scheduled, fixed facts.
• estar (está) is used for temporary states or current situations.

A meeting being planned as an online meeting is treated like a fixed characteristic of that meeting (part of how it is organized), so Brazilians naturally say:

• A reunião é online. = The meeting is (an) online (meeting).

You might hear A reunião está online only in a very specific, more literal sense, like “the meeting is currently online (as opposed to offline),” but this is much less common and often sounds odd for a planned event.

Yes, reunião is feminine, which is why the article is A (feminine singular) and not O (masculine singular).

Clues:

• It ends in -ão, which can be masculine or feminine, but reunião happens to be feminine.
• Adjectives and articles that go with it will be feminine:
  • a reunião importante (the important meeting)
  • esta reunião (this meeting)

You learn the gender with the noun: a reunião.

No. Online is an invariable adjective in Portuguese. It stays the same:

• A reunião é online. (The meeting is online.)
• As reuniões são online. (The meetings are online.)
• O evento é online. (The event is online.)
• Os eventos são online. (The events are online.)

You do not say onlines in normal Portuguese.

Brazilians use online all the time, especially in everyday speech and writing.

Other options you might see:

• A reunião é virtual. (The meeting is virtual.)
• A reunião é pela internet. (The meeting is via the internet.)
• A reunião é por videoconferência. (The meeting is by videoconference.)

But online is very common and natural.

In Brazilian Portuguese, reunião is typically pronounced roughly like:

• [hew-nee-AW̃]

Syllable breakdown:

• reu – sounds like “hew” or “hey-oo” blended
• ni – like “nee”
• ão – a nasal sound, similar to the “own” in English but with the vowel nasalized; you don’t fully pronounce the n.

Stress is on the last syllable: reu-ni-ÃO → reuniÃO.

Brazilians pronounce online with a Portuguese accent, usually something like:

• [on-LAJN] or [õn-LAJN]

Features:

• The o is like the o in “off” (depending on accent, it may sound nasal).
• The li often sounds close to English “lie”.
• Final -ne sounds like “n” or “ne” depending on the speaker.

You will also see the spelling on-line, especially in older texts, but online is now more common.

Yes, if the context is clear, Brazilians often drop the subject:

• Someone asks: Como vai ser a reunião? (How will the meeting be?)
• You answer: É online. (It’s online.)

Here, É online is understood as A reunião é online because the topic is already known.

You have a few natural options:

• A reunião vai ser online. – very common in speech (literally: “is going to be online”).
• A reunião será online. – a bit more formal / written style.

Both mean “The meeting will be online.”

The plural of reunião is reuniões.

• Singular: A reunião é online. (The meeting is online.)
• Plural: As reuniões são online. (The meetings are online.)

Changes:

• A → As (feminine singular → feminine plural)
• reunião → reuniões
• é → são (3rd person singular → plural of ser)
• online stays the same.

The accent ã plus o (ão) marks:

1. Stress on the last syllable: reu-ni-ÃO.
2. A nasal vowel sound (air goes through the nose).

Without the accent, reuniao would be both misspelled and pronounced incorrectly. So always write reunião.

No, that word order is not natural here.

The normal order is:

• Subject + verb + complement
• A reunião é online.

You might occasionally see something like A reunião, online, é mais prática, but Online é a reunião by itself sounds wrong in standard Brazilian Portuguese. The adjective normally comes after the verb ser in this kind of sentence.