delusion

Universal Words noun 1 [C] a false belief or opinion about yourself or your situation: the delusions of the mentally ill * Don't go getting delusions of grandeur (= a belief that you are more important than you actually are). * He was suffering from paranoid delusions and hallucinations. * Love can be nothing but a delusion. 2 [U] the act of believing or making yourself believe sth that is not true: He seems to have retreated into a world of fear and delusion.