WordWeb Online

1. A ridge of land that separates two adjacent river systems
   - water parting, divide
    
2. The entire geographical area drained by a river and its tributaries; an area characterized by all runoff being conveyed to the same outlet
   "flood control in the Missouri watershed";
   - river basin, basin, drainage basin, catchment area, catchment basin, drainage area
    
3. 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";
   - landmark, turning point, cusp

Derived forms: watersheds

Type of: geographic area, geographic region, geographical area, geographical region, juncture, line, occasion

Encyclopedia: Watershed, Bristol