watershed

American  

[waw-ter-shed, wot-er-] / ˈwɔ tərˌʃɛd, ˈwɒt ər- /

noun

1. Chiefly British. the ridge or crest line dividing two drainage areas; water parting; divide.

2. the region or area drained by a river, stream, etc.; drainage area.

3. Architecture. wash.

4. an important point of division or transition between two phases, conditions, etc..

   The treaty to ban war in space may prove to be one of history's great watersheds.

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adjective

1. constituting a watershed.

   a watershed area; a watershed case.

watershed British  

/ ˈwɔːtəˌʃɛd /

noun

1. the dividing line between two adjacent river systems, such as a ridge

2. an important period or factor that serves as a dividing line

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watershed Scientific  

/ wô′tər-shĕd′ /

1. A continuous ridge of high ground forming a divide between two different drainage basins or river systems.

2. The region enclosed by such a divide and draining into a river, river system, or other body of water.

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watershed Cultural  

1. A ridge of high land dividing two areas that are drained by different river systems. On one side of a watershed, rivers and streams flow in one direction; on the other side they flow in another direction. Also, the area drained by a water system.

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Discover More

By extension, a “watershed” is a critical point that serves as a dividing line: “The parties reached a watershed in the contract negotiations.”

Etymology

Origin of watershed

First recorded in 1795–1805; water + shed ²

Explanation

A watershed is a turning point, or historic moment. The day you got your braces off might have been a watershed moment in your life. Watershed is a geographical term, originally. The area that drains into a single river is the watershed for that river. Watershed can also mean a ridge, like that formed by a chain of mountains, which sends water to two different rivers on either side. It's from this meaning that watershed came to mean a turning point or dividing line in social life.

Example Sentences

This year, the snowpack in the upper portion of the river’s watershed in the Rocky Mountains measures just 22% of average, the smallest on record.

From Los Angeles Times • May 2, 2026

"This is a real watershed moment, we are thrilled," says Tony Armstrong, chief executive of Locality, the national network for community-led organisations.

From BBC • Apr. 30, 2026

The company, which is facing another watershed social-media trial this summer, has said it plans to appeal both verdicts.

From The Wall Street Journal • Apr. 29, 2026

In the late 90s and the 2000s, television programs still generated pop culture watershed moments that everyone experienced at once.

From Barron's • Apr. 8, 2026

Thereafter, except for a narrow band sprayed in 1956, the whole upper watershed of this branch was excluded from the spraying program.

From "Silent Spring" by Rachel Carson

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