watershed
definition: an event marking a unique or important historical change of course or one on which important developments depend
example: the agreement was a watershed in the history of both nations
speech part: noun
synonyms:
turning point
definition: the entire geographical area drained by a river and its tributaries
example:
speech part: noun
synonyms:
basin
definition: a ridge of land that separates two adjacent river systems
example:
speech part: noun
synonyms:
water parting
divide