turning point

noun5

1. •
   A crossroads.
2. •
   A decisive point at which a significant change or historical event occurs, or at which a decision must be made.

   • Another turning point, a fork stuck in the road / Time grabs you by the wrist, directs you where to go — 1997
3. •
   A T-junction.
4. •
   A place at which one changes their direction of travel.

   • Chicago was the turning point of my journey and I left there at midnight abroad ^([sic]) the "Chicagoan," an express of the New York Central System. — 1953
5. •
   A maximum or minimum on a graph.