pre-emption

from The Century Dictionary.

• noun The act of purchasing before others; also, the right of purchasing before others, as the right of a settler to a preference in the opportunity to buy land on or near which he has settled, or of an owner of the upland to buy lands under water in front of his shore, and, in England, the privilege once enjoyed by the king of buying provisions for his household at an appraisal, or in preference to others.
• noun Specifically, in international law. See the quotation.

from the GNU version of the Collaborative International Dictionary of English.

• noun engraving The privilege or prerogative formerly enjoyed by the king of buying provisions for his household in preference to others.
• noun The right of an actual settler upon public lands (particularly those of the United States) to purchase a certain portion at a fixed price in preference to all other applicants.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Alternative spelling of preemption.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the judicial principle asserting the supremacy of federal over state legislation on the same subject
• noun a prior appropriation of something
• noun the right to purchase something in advance of others
• noun the right of a government to seize or appropriate something (as property)
• noun a prior appropriation of something
• noun the right to purchase something in advance of others
• noun the judicial principle asserting the supremacy of federal over state legislation on the same subject
• noun the right of a government to seize or appropriate something (as property)