wa·​ter·​shed | \ ˈwȯ-tər-ˌshed How to pronounce watershed (audio) , ˈwä- \
plural watersheds

Definition of watershed

1a : 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 nouna watershed momenta watershed eventThe 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 nounBrain 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

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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."

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 And climate change is forecast to intensify precipitation over the region, meaning there could be more years ahead like 2018, which had record-setting rainfall across the watershed. Washington Post, "These farmers say they try to stem pollution, it’s expensive," 8 Feb. 2020 To protect nesting golden eagles, wildlife biologists with the Contra Costa Water District closed six trails in the watershed this week in areas near traditional nesting sites. Tom Stienstra, SFChronicle.com, "Hawks, eagles on full display at Contra Costa lake," 6 Feb. 2020 In recent years, however, surveys have found new, invasive species in the watersheds. Emma Austin, The Courier-Journal, "A Kentucky biologist discovered a new species, and you could name it," 24 Jan. 2020 In the Northeast, rains may increase, opening up new whitewater in places like the Adirondack watershed. Andrew Lewis, Outside Online, "Climate Change Is Transforming Wilderness Exploration," 20 Jan. 2020 The group is involved with dozens of schools in the watershed and hosts cleanup projects and other programs that the public is welcome to attend, McCormick said. Omar Abdel-baqui, Detroit Free Press, "50 years after Rouge River fire, Donald Trump policy may jeopardize decades of progress," 7 Oct. 2019 Clearing the full watershed will take an international effort. Omid Scobie, Harper's BAZAAR, "Prince Harry Retraces Princess Diana's Footsteps in Angola Minefields," 27 Sep. 2019 The Canal Authority presented its annual report last week highlighting that 2019 was one of the watershed’s lowest rain years in many decades, about 20 percent below the historic average. Juan Zamorano, BostonGlobe.com, "Panama Canal announces freshwater surcharge amid scant rains," 13 Jan. 2020 Similar protections of the watershed are already in the city code, Fritz said. oregonlive, "Portland voters to decide on new rules for Bull Run watershed, spending ratepayer money to help other cities," 28 Oct. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'watershed.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of watershed

1764, in the meaning defined at sense 1a

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The first known use of watershed was in 1764

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Last Updated

15 Feb 2020

Cite this Entry

“Watershed.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/watershed?pronunciation&lang=en_us&dir=w&file=waters02. Accessed 20 Feb. 2020.

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More Definitions for watershed


How to pronounce watershed (audio)

English Language Learners Definition of watershed

: a time when an important change happens
: a line of hills or mountains from which rivers drain : a ridge between two rivers
chiefly US : the area of land that includes a particular river or lake and all the rivers, streams, etc., that flow into it


wa·​ter·​shed | \ ˈwȯ-tər-ˌshed How to pronounce watershed (audio) , ˈwä- \

Kids Definition of watershed

1 : a dividing ridge (as a mountain range) separating one drainage area from others
2 : the whole area that drains into a lake or river

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