1. A boundary between territories, regions, or countries that has not been clearly established, demarcated, or officially agreed upon
The undefined border between the two nations has been a source of conflict for decades.
A fronteira indefinida entre as duas nações tem sido uma fonte de conflito há décadas.
2. In abstract contexts, a limit or boundary that lacks clear definition or distinction
There is an undefined border between professional and personal life in remote work.
Existe uma fronteira indefinida entre a vida profissional e pessoal no trabalho remoto.