preemption

Etymology

From Medieval Latin praeēmptiō (“previous purchase”), from praeemō (“buy before”), from Latin prae- (“before”) + emō (“buy”).

noun

1. An act or process that preempts; a preventive or forestalling action; as:
   1. The purchase of something before it is offered for sale to others.
   2. The purchase of public land by the occupant.
   3. (computing) The temporary interruption of a task without its cooperation and with the intention of resuming it at a later time.
   4. (law) The displacement of a lower jurisdiction's laws when they conflict with those of a higher jurisdiction.