watershed

noun

wa·​ter·​shed ˈwȯ-tər-ˌshed 

ˈwä-

plural watersheds

1

a

: a dividing ridge between drainage areas : divide entry 2

The watershed of the Himalayas does not lie along the line of its highest peaks, as in most mountain ranges, but about a hundred miles farther north.

—Frits Staal

b

: a region or area bounded peripherally by a divide and draining ultimately to a particular watercourse or body of water

the Mississippi River watershed

2

: a crucial dividing point, line, or factor : turning point

This year marked a watershed for contemporary classical music in the city.

—The Chicago Tribune

The spring of 1949 was, in general, a watershed in Joe Liebling's life.

—Raymond Sokolov

The death of Ugandan teacher Gregory Byaruhanga at the hands of the Kenyan police has marked a watershed in the rising tension in the region and in the instability of the Kenyan regime.

—Victoria Brittain

—often used before another noun

a watershed moment

a watershed event

The watershed year for science fiction must be 1968, when Stanley Kubrick's 2001: A Space Odyssey appeared, not only dramatically expanding for this kind of motion picture the potentials of film technology, but making science fiction a vehicle for both poetic vision and metaphysical exploration.

—Ira Konigsberg

3

British : the time of day after which television programs not appropriate for children may be broadcast

the nine o'clock watershed

4

medical : an area of tissue (as of the brain or colon) that is located at the periphery of two separate arterial systems, is dependent on both for blood supply, and may be poorly perfused and vulnerable to ischemia

—usually used before another noun

Brain imaging of patients with vascular dementia typically show small strokes or poor blood supply deep in the brain, at the natural terminal (the so-called watershed area) of the blood vessel.

—Renee Meyer

… cell death caused by blocked blood flow in the brain's "watershed" region, where two arteries supply blood.

—Susan Scutti

see also watershed infarction

Did you know?

Watershed Has Geographic Origins

Opinion on the literal geographic meaning of watershed is divided. On one side of the debate are those who think the word can only refer to a ridge of land separating rivers and streams flowing in one direction from those flowing in the opposite direction. That's the term's original meaning, one probably borrowed in the translation of the German Wasserscheide. On the other side of the argument are those who think watershed can also apply to the area through which such divided water flows. The latter sense is now far more common in America, but most Americans have apparently decided to leave the quarrel to geologists and geographers while they use the term in its figurative sense, "turning point."        

Synonyms

• climacteric
• climax
• corner
• landmark
• milepost
• milestone
• turning point

Examples of watershed in a Sentence

The show will not air until after the nine o'clock watershed.

a watershed moment in her life came when she inherited a reasonable sum of money and was able to start her own coffee shop

Recent Examples on the Web

In 2023 then-secretary of the interior Deb Haaland issued a 20-year administrative mineral withdrawal for 225,000 acres in the watershed. —Natalie Krebs, Outdoor Life, 11 June 2025

Droughts in the Amazon River in 2023 and 2024 caused more nitrogen and phosphorus to build up in the watershed. —Julia Jacobo, ABC News, 5 June 2025

Over 100 years ago, the land in the Shingle Creek watershed was platted and sold to people sight unseen. —Letters To The Editor, The Orlando Sentinel, 1 June 2025

But elsewhere in the watershed, on the lower Yuba River at Daguerre Point Dam, exists the point of contention. —Jake Goodrick, Sacbee.com, 29 May 2025

Word History

First Known Use

1764, in the meaning defined at sense 1a

Phrases Containing watershed

• watershed infarct
• watershed infarction
• watershed stroke

Rhymes for watershed

• abovesaid
• aforesaid
• arrowhead
• casinghead
• copperhead
• figurehead
• fountainhead
• gingerbread
• hammerhead
• infrared
• leatherhead
• letterhead

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Kids Definition

watershed

noun

wa·​ter·​shed ˈwȯt-ər-ˌshed 

ˈwät-

1

: a dividing ridge (as a mountain range) separating one drainage area from others

2

: the area that drains into a river or lake