noun🔗Share边境，边界。 The part of a country which borders or faces another country or unsettled region""The soldiers guarded the country's frontiers against any possible invasion from neighboring nations." "士兵们守卫着国家的边境，以防邻国可能的入侵。geographynationareapoliticsstateChat with AIVocabulary GamePractice Reading
noun🔗Share前沿, 前线 The most advanced or recent version of something; leading edge."the frontier of civilization"文明的前沿technologyscienceachievementChat with AIVocabulary GamePractice Reading
noun🔗Share前沿阵地，前哨阵地 An outwork of a fortification."The soldiers patrolled the frontiers of the castle's outer wall, watching for enemy movements. "士兵们在城堡外墙的前沿阵地巡逻，警惕地观察敌人的动向。militaryarchitecturewarChat with AIVocabulary GamePractice Reading
