Lavei a testa e o queixo com água fria antes da reunião.

Portuguese often drops the subject pronoun when the verb ending already makes the subject clear.

• Lavei = I washed
• The ending -ei shows it is eu in the past tense

So Lavei a testa... is a perfectly natural way to say I washed my forehead... in European Portuguese. You could say Eu lavei..., but that usually adds emphasis or contrast.

Lavei is the pretérito perfeito simples, the normal tense for a completed action in the past.

It comes from the verb lavar = to wash.

Conjugation:

• eu lavei = I washed
• tu lavaste = you washed
• ele/ela lavou = he/she washed
• nós lavámos = we washed
• vós lavastes = you washed
• eles/elas lavaram = they washed

In this sentence, lavei tells you the washing happened before the meeting and is viewed as a finished action.

With body parts, Portuguese very often uses the definite article instead of a possessive, especially when it is obvious whose body parts are meant.

So:

• Lavei a testa e o queixo = literally I washed the forehead and the chin
• but naturally it means I washed my forehead and chin

Using a minha testa and o meu queixo is possible, but it sounds more emphatic, more specific, or less natural in an ordinary sentence like this.

Because testa and queixo are two separate nouns, and each one normally takes its own article.

• a testa = the forehead
• o queixo = the chin

So a testa e o queixo is the normal structure. Portuguese usually does not drop the second article here.

Here com means with, in the sense of using something.

So:

• Lavei a testa e o queixo com água fria = I washed my forehead and chin with cold water

It tells you what was used for washing.

This is very natural Portuguese. It does not mean that the forehead and chin were together with cold water in some vague way; it clearly means cold water was the means used.

Água is feminine.

That is why the adjective is feminine:

• água fria = cold water

A common point of confusion is that when água has a singular definite article, Portuguese often uses a in writing but the sound may feel unusual because the word starts with a:

• a água
• esta água
• água fria

The adjective still agrees with the noun’s real gender, so it must be fria, not frio.

In your sentence there is no article before água, just:

• com água fria

Because antes is followed by de when it introduces a noun phrase.

So the basic structure is:

• antes de
  • noun

Then de combines with the article a in a reunião:

• de + a = da

So:

• antes da reunião = before the meeting

Other examples:

• antes do almoço = before lunch
• antes das aulas = before the classes
• antes de sair = before leaving

Notice that with a verb, you keep de:

• antes de sair

Yes. Portuguese allows some flexibility.

The original sentence:

• Lavei a testa e o queixo com água fria antes da reunião.

You could also say:

• Antes da reunião, lavei a testa e o queixo com água fria.

Both are correct. The second version puts more focus on the time expression before the meeting.

The original order is very natural and neutral.

Not in the same way, because lavei-me means I washed myself, which is much broader.

Compare:

• Lavei a testa e o queixo. = I washed my forehead and chin.
• Lavei-me. = I washed myself.

If you want to mention the specific body parts, lavei a testa e o queixo is the natural choice.

In Portuguese, especially with body parts, it is very common to name the body part directly rather than use a reflexive structure plus a possessive.

Yes, it sounds natural in European Portuguese.

It is straightforward and idiomatic:

• Lavei gives a completed past action
• a testa e o queixo is the normal way to refer to your own body parts here
• com água fria is natural
• antes da reunião is also fully standard

So this is a good model sentence for everyday Portuguese.