This is the 4870th most frequent Portuguese word.
fronteiras
Borders or boundaries.
Here, 'fronteiras' is used in the geographical sense to denote boundaries between countries.
As fronteiras entre os países delimitam territórios.
The borders between countries define territories.
In this sentence, 'fronteiras' is used metaphorically to describe conceptual limits or boundaries.
Devemos ultrapassar as fronteiras do pensamento para inovar.
We must surpass the boundaries of thought to innovate.
Here, 'fronteiras' refers to the extent or limits of knowledge fields, used figuratively.