n. 1. a. The right to purchase something before others, especially the right to purchase public land that is granted to one who has settled on that land. b. A purchase made by such a right. 2. Prior seizure of, appropriation of, or claim to something, such as property. 3. The action of preempting, as the use of military force in a preemptive attack. 4. Law The doctrine that federal law takes precedence over state law. [PRE- + Latin ēmptiō, ēmptiōn-, buying (from ēmptus, past participle of emere, to buy; see em- in the Appendix of Indo-European roots).] |
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