The meaning of the poem was subtle and elusive, challenging to grasp fully.

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 形容事物像要逃避捕捉一样难以捉摸或理解，常用来描述难以理解的概念或难以达成的目标。