A milestone is an important event in the history or development of something or someone.
例句
He said the launch of the party represented a milestone in Zambian history...他说该党的创立是赞比亚历史上的一个里程碑。Starting school is a milestone for both children and parents.对于孩子和家长而言，开始上学是一件大事。
N-COUNT
（路边显示到某地距离的）里程碑，里程标志
A milestone is a stone by the side of a road showing the distances to particular places.
英汉词典释义
n.
重要事件;重要阶段;转折点;里程碑
Several important milestones in foreign policy have been passed by this Congress and they can be chalked up as major accomplishments.这次代表大会通过了对外政策中几起划时代的事件,并且它们可作为主要成就记录下来。The company passed the ￡6 million milestone this year.今年公司越过了600 万英镑这个里程碑式的数字。The film proved to be a milestone in the history of cinema.事实证明这部影片是电影史上的一个里程碑。“Our work”, he continued, warming to his theme, “will be a milestone in scientific history.”“我们的工作， ”他说到这一话题来了劲，“将会是科学史上的里程碑。 ”
英英词典释义
Noun
1. stone post at side of a road to show distances
2. a significant event in your life (or in a project)