/ˈfrʌntɪə(r); US frʌnˈtɪər ||; frʌnˈtɪr/noun1 [C] the frontier (between A and B) the line where one country joins another; border 国界；边界: the end of frontier controls in Europe. 欧洲国家之间不再有边境检查 ☞Look at the note at border. 参看border的注释。
2 the frontiers [pl] the limit between what we do and do not know 知识的极限: Scientific research is constantly pushing back the frontiers of our knowledge about the world. 科学研究不断扩大我们对这个世界的认识。