watershed
n
(a) line of high land where streams on one side flow into one river or sea and streams on the other side flow into a different river or sea 分水线; 分水岭.
(b) (fig 比喻) turning-point in a course of events 事情发展中的转折点
Her visit to India proved to be a watershed in her life. 她的印度之行成了她一生的转折点.