[pre.emp.tion] n [ML praeemption-, praeemptio previous purchase, fr. praeemere to buy before, fr. L prae- pre- + emere to buy--more at redeem] (1602) 1 a: the right of purchasing before others; esp: one given by the government to the actual settler upon a tract of public land b: the purchase of something under this right
2: a prior seizure or appropriation: a taking possession before others