Frontiers adjectives are listed in this post. Each word below can often be found in front of the noun frontiers in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing FRONTIERS.
american, colonial, cultural, distant, eastern, european
extensive, extreme, far, french, geographical, german
imperial, indian, international, last, many, military
national, natural, new, northern, old, other
own, political, present, remote, respective, roman
russian, southern, very, western
Hope this word list had the adjective used with frontiers you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.