1 to go back the same way you came 循原路返回: We got lost in the wood and had to backtrack. 我们在林子中迷失了方向，不得不循原路返回。

2 backtrack (on sth) to change your mind about a plan, promise, etc that you have made 改变主意；出尔反尔: Unions forced the company to backtrack on its plans to close the factory. 工会迫使公司改变关闭工厂的计划。