1.Definition: a ridge of land that separates two adjacent river systems

Related Noun(s):divide, water parting

Category: Places

2.Definition: an event marking a unique or important historical change of course or one on which important developments depend

"The agreement was a watershed in the history of both nations"

Related Noun(s):landmark

Category: General

3.Definition: the entire geographical area drained by a river and its tributaries; an area characterized by all runoff being conveyed to the same outlet

Related Noun(s):basin, catchment area, catchment basin, drainage area, drainage basin, river basin

Category: Places