preemption

noun5

1. •
   An act or process that preempts; a preventive or forestalling action.
2. •
   The supersession of a conflicting law from a lower jurisdiction by an overlapping law from a higher jurisdiction.
3. •
   The temporary interruption of a task without its cooperation and with the intention of resuming it at a later time.
4. •
   The purchase of something before it is offered for sale to others.
5. •
   The purchase of public land by the occupant.