to make something, especially a pay increase, effective from an earlier timeto make something, especially a pay increase, effective from an earlier time
使（尤指涨工资）在较早的时间生效 They got a pay rise in March that was backdated to January. 他们3月份涨了工资，而实际加薪是从1月份算起的。
the process of making a law or decision effective from a date before it was approved:the process of making a law or decision effective from a date before it was approved:
The legal profession is concerned that retroaction would cause an unmanageable wave of new cases.
