1. to make a particular outcome inevitable or certain, especially a negative one; to determine someone's future in a decisive way
His decision to quit school sealed his fate as an unemployed man.
Sua decisão de largar a escola selou seu destino como um homem desempregado.
2. to commit oneself to a course of action that cannot be reversed
When she signed the contract, she sealed her fate.
Quando ela assinou o contrato, selou seu destino.