/dɪˈluː.ʒən/
a false belief or opinion about yourself or your situation 错觉；谬见；妄想
the delusions of the mentally ill
精神病患者的妄想
Don’t go getting delusions of grandeur (= a belief that you are more important than you actually are).
不要变得妄自尊大。
delusional:
He showed signs of delusional thinking near the end of his life.
他在生命的最后时刻出现了妄想的症状。
If you think we can afford a new car, you are delusional.
如果你觉得我们能买得起新车，那你就是在妄想