preemptverb [ T ]
us/priˈempt/to prevent something from happening by taking action first:
State laws preempted local governments from restricting newspaper displays.
If a broadcast is preempted, it is replaced by another, usually more important broadcast:
One station preempted its Friday night schedule to televise the high school playoffs.
preemptive
adjective [ not gradable ] also pre-emptive us/priˈemp·tɪv/
a preemptive air strike on an enemy base