"Turning on a dime" is a commonly used phrase to describe sudden and quick changes in direction or decisions. However, there are several synonyms that can also be used to convey this meaning. One such synonym is "pivot," which implies a sudden shift in direction that occurs as if on a pivot. Another synonym is "change course," which refers to a deliberate alteration in direction or plan. "Shift gears" is another synonym that can be used when someone needs to quickly adjust their approach or mindset. Finally, "switch directions" can also be used to describe a sudden change in course or perspective.