delusion
noun [ C or U ] uk/dɪˈluː.ʒən/ us/dɪˈluː.ʒən/
幻想；错觉
belief in something that is not true
[ + that ] He's under the delusion that he will be promoted this year. 他怀有自己今年会得到晋升的错觉。
Idiom
delusions of grandeuridiom 自大，自命不凡
the belief that you are more important or powerful than you really are