1. A border or boundary line that has been formally defined, demarcated, and officially recognized between two territories, nations, or regions
The established border between the two countries was marked by a fence and guarded posts.
A fronteira estabelecida entre os dois países foi marcada por uma cerca e postos de guarda.
2. A fixed or agreed-upon limit or boundary that has been set and is no longer disputed
The established frontier of the national park protects the ecosystem within its boundaries.
A fronteira estabelecida do parque nacional protege o ecossistema dentro de seus limites.