pre·empt or pre-empt
v. pre·empt·ed, pre·empt·ing, pre·empts
1. To appropriate, seize, or take for oneself before others. See Synonyms at appropriate.
2. To take the place of; displace: A special news program preempted the scheduled shows.
3. To have precedence or predominance over: Discussion of the water shortage will preempt the other topics on this week's agenda.
4. To gain possession of by prior right or opportunity, especially to settle on (public land) so as to obtain the right to buy before others.
Another example: The airing of Oprah Winfrey's Legends Ball has been pre-empted by tonight's Presidential address. It will air next Monday. (This is true check your local listings.)