WordWeb Online

1. (psychology) an erroneous belief that is held in the face of evidence to the contrary
   - psychotic belief
    
2. A mistaken or unfounded opinion or idea
   "he has delusions of competence";
   - hallucination
    
3. The act of deluding; deception by creating illusory ideas
   "She has a delusion that she is being spied on.";
   - illusion, head game

Derived forms: delusions

Type of: deceit, deception, dissembling, dissimulation, mental condition, mental state, misconception, psychological condition, psychological state

Encyclopedia: Delusion