ADJ. important, major, significant | cultural, historical, political
VERB + WATERSHED be, mark, represent | reach
WATERSHED + VERB divide sth Darwin's theory of evolution was a watershed dividing the old way of thinking from the new.
PREP. ~ between The 19th century marked a watershed between the country's agricultural past and its industrial future. | ~ for The granting of the vote represented a watershed for the rights of women. | ~ in With the strike, a historical watershed in the development of the trade union movement was reached.