A ridge or stretch of high land that separates waters flowing to different rivers, basins, or seas. The Continental Divide is the principal watershed of North America.
(chiefly North American) An area or region whose rivers and streams all flow into a particular body of water; a drainage basin. Conservation efforts are focused on protecting the entire Mississippi River watershed.
A pivotal event or turning point that marks a significant change in the course of affairs. The invention of the internet was a watershed in the development of global communication.