watershed

/ˈwɔtərʃɛd/
noun
  1. An event or point in time that marks an important change or turning point.
    • The new law represented a watershed in environmental protection.
    • The invention of the internet was a watershed in how people communicate.
    • Winning the championship was a watershed moment for the young team.
  2. The area of land where all the water drains into a particular river, lake, or ocean.
    • The Mississippi River watershed covers a huge part of the United States.
    • Heavy rain caused flooding throughout the entire watershed.
    • Farmers in the watershed must be careful not to pollute the streams.
  3. A ridge or line of high ground that separates two drainage basins.
    • The hikers reached the watershed and could see valleys on both sides.
    • The trail follows the watershed for several miles.
    • This mountain range forms the watershed between the two rivers.
Synonyms