the frontier
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 → frontierExamples from the Corpusthe frontier• Alaska is known as the last frontier.• Wilder's novel is about a family's struggle on the American frontier.