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 noun a 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 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

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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 The dam blocks the eels’ typical migration patterns and their access to parts of the watershed. Washington Post, 15 Sep. 2021 The trends are similar in the other parts of the watershed where pumping isn’t regulated. Ian James, AZCentral.com, 6 Sep. 2021 Just in July, certain areas of the watershed received as much as 10 inches of rain. Clara Migoya, The Arizona Republic, 31 Aug. 2021 This year is proving to be something of a watershed for user privacy. Zak Doffman, Forbes, 4 May 2021 From 2015 to 2018, the conservancy completed its Save1000Acres campaign, preserving just under 1,000 acres in the northern section of the watershed. Linda Mcintosh, San Diego Union-Tribune, 13 Apr. 2021 Melanie Winter, founder and director of the River Project, said 85% of the Ballona Creek watershed has been urbanized. Los Angeles Times, 8 Apr. 2021 Industry officials pointed to studies by a neighboring regulatory agency, the Susquehanna River Basin Commission, that found no link between intensive gas drilling in the Marcellus and degradation of the watershed. Michael Rubinkam, ajc, 25 Feb. 2021 Despite public protests and courtroom trials, though, none of the Sacklers involved with Purdue have ever before appeared publicly to address the anger and criticism, which made the congressional hearing something of a watershed in the ongoing saga. Ed Silverman @pharmalot, STAT, 17 Dec. 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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Dictionary Entries Near watershed

water shamrock


watershed infarction

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Last Updated

15 Oct 2021

Cite this Entry

“Watershed.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/watershed. Accessed 21 Oct. 2021.

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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
: 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

More from Merriam-Webster on watershed

Nglish: Translation of watershed for Spanish Speakers

Britannica English: Translation of watershed for Arabic Speakers

Britannica.com: Encyclopedia article about watershed


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