From Longman Dictionary of Contemporary Englishthe frontierthe frontierSGan area where people have never lived before, that not much is known about, especially in the western US before the 20th century a novel about a family’s struggle on the American frontier space, the final frontier → frontier
Examples from the Corpus
the frontier• Alaska is known as the last frontier.• Wilder's novel is about a family's struggle on the American frontier. 