1. A door that has not been opened; literally a closed door
The unopened door at the end of the hallway intrigued the children.
A porta fechada no final do corredor intrigava as crianças.
2. Figuratively, an opportunity or possibility that has not been explored or utilized
She refused to leave any unopened doors in her career path.
Ela recusou deixar nenhuma oportunidade inexplorada em seu caminho profissional.