watershed
noun
[ ˈwɔːtəʃɛd ]
• an area or ridge of land that separates waters flowing to different rivers, basins, or seas.
• an event or period marking a turning point in a situation.
• "these works were a watershed in the history of music"
Origin:
early 19th century: from water + shed in the sense ‘ridge of high ground’ (related to shed2), suggested by German Wasserscheide .
