[ 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

First recorded in 1795–1805; water + shed2

Example sentences from the Web for watershed

British Dictionary definitions for watershed

/ (ˈwɔːtəˌʃɛd) /


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

Medical definitions for watershed

[ wôtər-shĕd′ ]


A ridge between two areas that directs drainage to either side.
The area of marginal blood flow at the extreme periphery of a vascular bed.
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.

Scientific definitions for watershed

[ wôtər-shĕd′ ]

A continuous ridge of high ground forming a divide between two different drainage basins or river systems.
The region enclosed by such a divide and draining into a river, river system, or other body of water.

Cultural definitions for watershed


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.

notes for watershed

By extension, a “watershed” is a critical point that serves as a dividing line: “The parties reached a watershed in the contract negotiations.”