preempt - Dictionary definition and meaning for word preempt
PRE+EMPTY = force to empty a place in order to occupy a prior right to buy.
PREEMPTIVE MEASURES :measures taken b4 sth gets worse or to prevent mishap
divide it like - PRE(means BEFORE) + EMPT(EMPTY)......IMAGINE YOU get the news that there is a bomb in your room.... you EMPTY the ROOM WITHOUT DETECTING IT ..so as to PREVENT, in advance, any kind of mishap.
(pre+attempt) attempt(empt) and acquire land or something earlier(pre)inorder to prevent others from acquiring it. You can also imagine that after buying u have replaced the earlier landlord.That counts for another meaning.
preempt = pre + empt = pre + employ = employ or act in advance
basically it is taken from praeemere means to buy before others comes and purchase it...SO YOU buy IN ADVANCE INORDER to prevent COMPETITION, YOU DISPLACE others by buying that land.