pre·emp·tion /-ˈɛm(p)ʃən/
  先買,先買權
  preemption
  占先
  Pre·ëmp·tion n.  The act or right of preemption.
  Specifically: (a) The act or right of purchasing before others. (b) The privilege or prerogative formerly enjoyed by the king of buying provisions for his household in preference to others. [Eng.] (c) 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. --Abbott.
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  pre-emption
       n 1: the judicial principle asserting the supremacy of federal
            over state legislation on the same subject [syn: preemption]
       2: the right of a government to seize or appropriate something
          (as property) [syn: preemption]
       3: the right to purchase something in advance of others [syn: preemption]
       4: a prior appropriation of something; "the preemption of
          bandwidth by commercial interests" [syn: preemption]
  preemption
       n 1: the judicial principle asserting the supremacy of federal
            over state legislation on the same subject [syn: pre-emption]
       2: the right of a government to seize or appropriate something
          (as property) [syn: pre-emption]
       3: the right to purchase something in advance of others [syn: pre-emption]
       4: a prior appropriation of something; "the preemption of
          bandwidth by commercial interests" [syn: pre-emption]