frontiernoun [C]uk /ˈfrʌn.tɪər/ /frʌnˈtɪər/ us /frʌnˈtɪr/
- The frontier is patrolled by border guards.
- At the frontier, there were people pestering tourists for cigarettes, food or alcohol.
- Two armed men were caught trying to cross the frontier at night.
- Air pollution is no respecter of national frontiers.
- The president pledged to respect the existing frontiers between the two countries.