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[waw-ter-shed, wot-er-] /ˈwɔ tərˌʃɛd, ˈwɒt ər-/
Chiefly British. the ridge or crest line dividing two drainage areas; water parting; divide.
the region or area drained by a river, stream, etc.; drainage area.
Architecture, wash (def 44).
an important point of division or transition between two phases, conditions, etc.:
The treaty to ban war in space may prove to be one of history's great watersheds.
constituting a watershed:
a watershed area; a watershed case.
Origin of watershed
1795-1805; water + shed2 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for watershed
Contemporary Examples
Historical Examples
  • To the North the view extended right up to the watershed of the Brahmaputra, 80 to 100 miles distant.

    Mount Everest the Reconnaissance, 1921 Charles Kenneth Howard-Bury
  • It follows the watershed from the lake to Oneida, and clears the Mohawk Valley northward.

    The Trail Book Mary Austin
  • The watershed between the river and Fingal's Creek is here only a high swell, and straight toward the west it is level as a floor.

    The Price of the Prairie Margaret Hill McCarter
  • The watershed of the Sutlej and Jamna runs through the tract.

  • A few years ago planting was undertaken on the watershed of the Colorado Springs, Colorado, reservoir.

    Our National Forests Richard H. Douai Boerker
British Dictionary definitions for watershed


the dividing line between two adjacent river systems, such as a ridge
an important period or factor that serves as a dividing line
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for watershed

"line separating waters flowing into different rivers," 1803, from water (n.1) + shed "ridge of high ground between two valleys or lower ground, a divide" in the topographical sense, perhaps from shed (v.) in its extended noun sense of "the part of the hair of the head" (14c.). A loan-translation of German Wasser-scheide. Figurative sense is attested from 1878. Meaning "ground of a river system" is from 1878.

Online Etymology Dictionary, © 2010 Douglas Harper
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watershed in Medicine

watershed wa·ter·shed (wô'tər-shěd')

  1. A ridge between two areas that directs drainage to either side.

  2. The area of marginal blood flow at the extreme periphery of a vascular bed.

  3. Ridges of the lumbar vetebrae and the pelvic brim formed in the abdominal cavity, which determine the direction in which a free effusion will gravitate when the body is supine.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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watershed in Science
  1. A continuous ridge of high ground forming a divide between two different drainage basins or river systems.

  2. The region enclosed by such a divide and draining into a river, river system, or other body of water.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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watershed in Culture

watershed definition

A ridge of high land dividing two areas that are drained by different river systems. On one side of a watershed, rivers and streams flow in one direction; on the other side they flow in another direction. Also, the area drained by a water system.

Note: By extension, a “watershed” is a critical point that serves as a dividing line: “The parties reached a watershed in the contract negotiations.”
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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