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 With so many trees gone, millions more gallons of polluted stormwater will enter the Cedar Rapids watershed. Dustin Renwick, Environment, "How one city plans to recover from losing most of its trees," 10 Dec. 2020 Borg suspects that the spraying of herbicides by timber companies is hurting the animals in Lake Nipigon’s watershed. Tim Folger, National Geographic, "North America’s most valuable resource is at risk," 17 Nov. 2020 Quartermaster Reach is the northernmost section of Tennessee Hollow, the watershed for much of the Presidio. John King, SFChronicle.com, "Crissy Field has new neighbors — 7 acres of tidal wetlands and a hilltop park-to-be," 11 Dec. 2020 Lutz said the goal of the report card is to provide decision makers and others with information to develop a collaborative approach to managing the watershed. Jim Salter, Star Tribune, "Water quality, flooding mean low grade for major watershed," 8 Dec. 2020 Preserving the land will help sequester carbon, improve water quality in the watershed, conserve biodiversity and protect pollinator habitat, the conservancy said. Deborah Sullivan Brennan, San Diego Union-Tribune, "Conservancy to preserve more than 100 acres near Lake Hodges," 2 Dec. 2020 Biden has also supported the Great Lakes Restoration Initiative, an EPA program working to protect the ecosystem and watershed. Meredith Colias-pete, chicagotribune.com, "Trump critics say EPA should have more inspections, enforcement under Biden," 27 Nov. 2020 Along with most of the dendritic system of tributaries that drained the Uptown New Orleans watershed, the scenic spot fell victim to three phases of drainage history. Richard Campanella, NOLA.com, "A 'lake' in Broadmoor? A natural paradise once graced Uptown's last tract to be developed," 30 Oct. 2020 The Trump administration buried a Forest Service analysis on the environmental effects of mining in the Boundary Waters region, likely because that study validates Obama-era conclusions that mining would be too damaging in the watershed, Rom said. Abby Smith, Washington Examiner, "GOP fears Alaska gold mine politics could stymie support for other projects," 10 Sep. 2020

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

12 Jan 2021

Cite this Entry

“Watershed.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/watershed. Accessed 17 Jan. 2021.

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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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