If you describe something as illusory, you mean that although it seems true or possible, it is in fact false or impossible.
例句
His freedom is illusory.他的自由是虚幻的。...the illusory nature of nationhood.国家的虚假本质
英汉词典释义
adj.
<正>貌似真实的;虚幻的
It seemed to an idealistic and illusory dream.那似乎是个不切实际、理想主义的美梦。
英英词典释义
Adjective
1. based on or having the nature of an illusion;
"illusive hopes of of finding a better job""Secret activities offer presidents the alluring but often illusory promise that they can achieve foreign policy goals without the bothersome debate and open decision that are staples of democracy"