U–turn 
/ˈju:ˌtɚn/ noun
plural U–turns /ˈju:ˌtɚn/ noun [count] 1 : a turn that you make while driving a car, walking, etc., that causes you to begin going in the opposite direction : a 180-degree turn
▪ The driver made/did a quick U-turn and headed back north. ▪ It's illegal to make a U-turn at this intersection. 2 informal : a complete change of ideas, plans, etc.
▪ She did/made a U-turn when she found out how much the renovation would cost.
▪ The driver made/did a quick U-turn and headed back north. ▪ It's illegal to make a U-turn at this intersection.
▪ She did/made a U-turn when she found out how much the renovation would cost.
