Formal:
* Adeus: This is the most formal way to say goodbye, similar to "farewell" in English.
* Até breve: This means "see you soon" and is used for a more formal goodbye when you expect to see the person again soon.
* Até mais: This means "see you later" and is a slightly less formal version of "até breve".
Informal:
* Tchau: This is the most common way to say goodbye in informal settings, similar to "bye" in English.
* Até logo: This means "see you soon" and is used when you expect to see the person again relatively soon.
* Até: This is a shorter, more casual way of saying "até logo".
* Valeu: This means "thanks" or "that's all" and is a very informal way to say goodbye. It's often used among friends.
Other:
* Boa noite: This means "good night" and is used when saying goodbye at the end of the day.
* Bom dia: This means "good morning" and can also be used as a way to say goodbye at the beginning of the day.
The best way to say goodbye depends on the situation and your relationship with the person you're talking to.