: a dividing ridge between drainage areas : divideentry 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
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 speakers have apparently decided to leave the quarrel to hydrologists and geographers, choosing to limit their use of watershed to its figurative “turning point” sense.
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
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Local contractor Kev Woolboy was helping coordinate response efforts, checking watersheds along the highway, as floodwaters from as far as 60 miles away raced toward town.—
Adam Burke,
NPR,
4 Nov. 2026 Its plan identified thousands of septic systems within the watershed, reportedly with 80% within a thousand feet of a lake.—
Joseph States,
Chicago Tribune,
2 Nov. 2026 The last substantial changes to the plan date back to 1995 for much of the watershed.—
Ian James,
Los Angeles Times,
30 Oct. 2026 Charlotte’s water restrictions remain in place for now because the watershed hasn’t fully recovered, said Jennifer Frost, public affairs manager for Charlotte Water.—
Nick Sullivan,
Charlotte Observer,
24 Oct. 2026 See All Example Sentences for watershed
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