Formal:
* Desistente: This is the most literal translation and refers to someone who gives up, especially in a specific situation.
* Abdicante: This means someone who gives up power or responsibility.
* Renunciante: This refers to someone who gives up something they have, like a claim or a right.
Informal:
* Desanimado: This means someone who is discouraged or disheartened, and might give up.
* Desistente: This can also be used informally, but it implies a more conscious decision to give up.
* Fraco: This means someone who is weak or lacking in willpower, and might give up easily.
Figurative:
* Que joga a toalha: This literally translates to "who throws in the towel," and is a common idiom for someone who gives up.
* Que desiste: This is another common idiom that means to give up.
Example:
"Ele era um desistente, nunca terminava o que começava." (He was a quitter, he never finished what he started.)
"Ela era uma desanimada, mas seu marido a apoiou e ela conseguiu superar o obstáculo." (She was discouraged, but her husband supported her and she managed to overcome the obstacle.)
The best choice depends on the specific context and the tone you want to convey.