ultimatum

1. N-COUNT An ultimatum is a warning to someone that unless they act in a particular way, action will be taken against them. 最后通牒

They issued an ultimatum to the police to rid the area of racist attackers, or they will take the law into their own hands. 他们向警方发出了最后通牒，要他们清除掉该地区的种族主义袭击者，否则他们就要自行采取行动。