From Longman Dictionary of Contemporary Englishwatershedwa‧ter‧shed /ˈwɔːtəʃed $ ˈwɒːtər-, ˈwɑː-/ noun [singular] 1 CHANGE/BECOME DIFFERENTan event or time when important changes happen in history or in your life SYN turning pointwatershed in The 1932 election represented a watershed in American politics.watershed decision/case etc a watershed case on pension rights2 → the (9 o'clock) watershed3 SG technical the high land separating two river systems
Examples from the Corpus
watershed• It is very convenient, for the presentation of historical accounts, when a specific date can be identified as a watershed.• The local council elections in May appeared to be a watershed in the party's and, therefore Mrs Thatcher's fortunes.• That wedding between Liz and Owen had proved to be a watershed in all their lives.• Nizan was convinced that February 1934 was a watershed not only in terms of cultural politics, but also in terms of cultural production.• This can be thought of as a cultural watershed.• And there are neighbouring glens on the east side of the watershed, also lovely and deserving of special mention.• The plan was for another military road over the watershed between Dee and Spey.watershed decision/case etc• Male speaker It's a watershed decision.Origin watershed (1800-1900) water + shed “line of high ground” ((16-21 centuries)) (from Old English scead “separation”); suggested by German wasserscheide 