(idiom) to have no basis in fact; to be completely fictitious or the product of one's imagination

A famous Han dynasty poem by [[司马相如|司馬相如|si1 ma3 xiang1 ru2]] about the fictional characters [[子虚|子虛|zi3 xu1]], [[乌有|烏有|wu1 you3]], and [[亡是公|亡是公|wu2 shi4 gong1]] used to criticize the extravagance of the emperor