If something such as an event is a watershed in the history or development of something, it is very important because it represents the beginning of a new stage in it.
例句
The election of Mary Robinson in 1990 was a watershed in Irish politics...1990年瑪麗·魯賓遜的當選是愛爾蘭政治上的一個轉折點。Tonight could prove to be a watershed for the international career of Barnes.今晚將可能成為巴恩斯國際職業生涯的轉折點。
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(成人電視節目播出前的)分水嶺時間
The watershed is a time before which television broadcasters have agreed not to show programmes unsuitable for children, for example programmes that contain scenes of sex or violence.
例句
Bad language before the watershed is widely resented...在成人節目時間之前出現的臟話深為眾人憎惡。The advert should only be shown after the 9pm watershed.這則廣告只能在晚上9點成人節目開始后才能播出。
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分水線；分水嶺
A watershed is an area of high ground which divides two or more river systems, so that all streams on one side flow into one river and those on the other side flow into a different river.
英漢詞典釋義
n.
轉折點
Our marriage was at a watershed.我們的婚姻到了一個轉折關頭。
英英詞典釋義
Noun
1. a ridge of land that separates two adjacent river systems
2. an event marking a unique or important historical change of course or one on which important developments depend;
"the agreement was a watershed in the history of both nations"