Delusional

1. The act or process of deluding.
2. The state of being deluded.
2. A false belief or opinion: labored under the delusion that success was at hand.
3. Psychiatry. A false belief strongly held in spite of invalidating evidence, especially as a symptom of mental illness: delusions of persecution.


[Middle English delusioun, from Latin dlsi, dlsin-, from dlsus, past participle of dldere, to delude. See delude.]