To take action in order to prevent an anticipated event from happening. The government decided to preempt the strike by negotiating with the union leaders.
To acquire or appropriate something in advance. The company preempted the new technology by securing the patent before its competitors.
To replace or displace something, especially a scheduled broadcast, with another program. The special news report preempted the regular television show.
Law: to render (a lower-level law or regulation) inoperative by the exercise of a superior authority. The federal statute preempts any conflicting state law.