1. An area of land at or near a border between countries or regions; a borderland region
The frontier field between the two nations was heavily fortified.
O campo de fronteira entre as duas nações era fortemente fortificado.
2. An unexplored or undeveloped area; a region at the edge of settled territory
The American West was considered a frontier field during the 19th century.
O Oeste americano era considerado um campo de fronteira durante o século XIX.
3. In academic or professional contexts, an emerging area of study or development
Artificial intelligence represents a frontier field in modern technology.
A inteligência artificial representa um campo de fronteira na tecnologia moderna.