From Longman Dictionary of Contemporary Englishdelusionde‧lu‧sion /dɪˈluːʒən/ noun 1 [countable, uncountable]BELIEVE a false belief about yourself or the situation you are inunder a delusion (that) He is under the delusion that I am going to cheat him.2 → delusions of grandeur —delusive /-sɪv/ adjective —delusional adjective
Examples from the Corpus
delusion• Belief in utopian progress is increasingly seen as a delusion.• We sat in the packed aisles, the building's relative simplicity a delusion for what was to follow.• She now had to finally forget the dreams and delusions of her youth• The stress of the day had given her delusions.• And wisdom usually follows illusion, delusion, and disillusion.• It appears to apply also, for example, to psychotic delusions.• Britain's weak balance of payments was not, however, a statistical delusion or the result of a reaction to one.• He was then, still, suffering delusions.• I was still under the delusion that everyone was trying to cheat me.• The Foundation has fostered this delusion assiduously. 