• synonyms


[waw-ter-shed, wot-er-]
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  1. Chiefly British. the ridge or crest line dividing two drainage areas; water parting; divide.
  2. the region or area drained by a river, stream, etc.; drainage area.
  3. Architecture. wash(def 44).
  4. 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.
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  1. constituting a watershed: a watershed area; a watershed case.
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Origin of watershed

First recorded in 1795–1805; water + shed2
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for watershed


  1. the dividing line between two adjacent river systems, such as a ridge
  2. an important period or factor that serves as a dividing line
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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

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.

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Online Etymology Dictionary, © 2010 Douglas Harper

watershed in Medicine


  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 vertebrae 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.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

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.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

watershed in Culture


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.

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