An attack launched as a defensive measure.

(law) The right of shareholders to maintain a constant percentage of a company's shares by receiving a proportionate fraction of any new shares issued, thus preempting any dilution

in a preemptive manner

plural of preemptive strike

capable of being preempted

(computing) Capable of being preempted.

One who preempts; especially one who appropriates public land.

plural of preemptor

Pertaining to preemption.

One who holds a prior right to purchase certain public land.