D defs.my
Entry 3 senses Webster, 1913

Delusion

/dĭl-o͞ozh'-ən/ · De·lu·sion · IPA /dɪˈl(j)uːʒ(ə)n/
01 n. The act of deluding; deception; a misleading of the mind.
  1. 1.
    The act of deluding; deception; a misleading of the mind.
  2. 2.
    The state of being deluded or misled.
  3. 3.
    That which is falsely or delusively believed or propagated; false belief; error in belief.
    “And fondly mourned the dear delusion gone.” Prior.
Syn. Delusion, Illusion.