"line separating waters flowing into different rivers," 1803, from water (n.1) + shed in a topographical sense of "ridge of high ground between two valleys or lower ground, a divide," perhaps from shed (v.) in its extended noun sense of "the part of the hair of the head" (14c.). Perhaps a loan-translation of German Wasser-scheide. Figurative sense is attested from 1878. Meaning "ground of a river system" is from 1878.
权威例句
1. The advert should only be shown after the 9pm watershed.
这则广告只能在晚上9点成人节目开始后才能播出。
2. The meeting has the potential to be a watershed event.
这次会议有可能成为具有转折性的事件。
3. Bad language before the watershed is widely resented.
在成人节目时间之前出现的脏话深为众人憎恶。
4. The middle decades of the 19th century marked a watershed in Russia's history.