make-believe
noun [ U ] disapproving uk/ˈmeɪk.bɪˌliːv/ us/ˈmeɪk.bɪˌliːv/
虚幻，假想
believing or imagining things that appear to be attractive or exciting, but are not real
The ideal of a perfectly fair society is just make-believe. 要社会完全公平的理想只是幻想而已。
He lives in a world of make-believe/make-believe world. 他生活在虚幻的世界里。