pre-emption
[pri'empʃn]
	    - n. 优先购买权;收买权
 
英语释意
- 1. the judicial principle asserting the supremacy of federal over state legislation on the same subject
 
- 2. the right of a government to seize or appropriate something (as property)
 
- 3. the right to purchase something in advance of others
 
- 4. a prior appropriation of something;
 - "the preemption of bandwidth by commercial interests"