1. the border between two countries or regions
2. the edge of settled or developed territory, especially in the American West
Usage: historical
3. the limits of knowledge or achievement in a particular field
Usage: figurative

Examples

• The soldiers patrolled the frontier between the two nations.
• Pioneers crossed the frontier to settle new lands in the West.
• Life on the frontier was harsh and dangerous.
• Scientists are exploring the frontiers of space research.
• Medical researchers are pushing the frontiers of cancer treatment.
• The frontier town had only a few wooden buildings.
• Digital technology represents the new frontier of education.