For many, true happiness can be an elusive dream that seems ever further from us.

elusive 是形容词，由动词 elude（逃避、躲避）加上形容词后缀 -ive 构成。elude 本身来自拉丁语，意思是"逃避、躲避"。elusive 形容某事物"难以捉摸的""难以获得的"，就像想要抓住却总是抓不住的东西。在这里形容"幸福"这种看似近在咫尺却又难以真正获得的状态。