(1) 1) 边界(境)(boundary between countries) [C] [N(between)/(with)]：the～between the Unite States and Canada 美国和加拿大边境;have～s with Norway and Finland与挪威和芬兰相邻;cross the～跨过边境;guard the～against invasions守卫边境防止入侵; a town on the～一个边境城镇;〖同〗 border，boundary line，limits，edge，extreme，confines，march;〖反〗interior; 2) 边境任一侧的土地(land on the border) [C] [作attrib]：a～zone/town 边境地带/城镇;～disputes/incidents/justice边境争端/事件/司法;～guards边防战士;

(2) 边境(边远)地区(land that forms the furthest extent of a country's settled or inhabited regions) [C，the～] (尤AmE)：beyond/near/on the～越过已开发地区/靠近边远地区/在边远地区;settle the～定居边疆;〖同〗outskirts;territories;〖反〗interior;

(3) (尤指知识)尖端(the limits or boundaries of knowledge，etc) [pl]：at the～of space exploration在太空探索的尖端知识方面;beyond the～of knowledge超过了尖端知识的范畴;advance/explore the～s of science 推进/探索科学的最新发展;The～s of medicine are moving all the time. 医学的尖端技术一直在向前发展。

→ fron′tiersman n 边疆居民;拓荒的人;

【辨异】frontier与border和boundary的区别见BORDER。