The phrase "turned on a dime" typically refers to the ability to quickly change direction or make a sudden maneuver. Some synonyms for this phrase might include "turned on a penny," "changed course abruptly," "made a hairpin turn," "pivoted on a whim," "reversed direction swiftly," or "made a sharp turn." Other phrases that imply quick and decisive movements might also be used in place of "turned on a dime," such as "swerved sharply," "made an about-face," "did a 180," or "took a sudden turn." All of these phrases convey the sense of agility and responsiveness that comes from being able to turn at a moment's notice.