A delusion is a belief that has no evidence in fact — a complete illusion. The cook at the hot dog stand who thinks he is the best chef in the world? That opinion is definitely a delusion.

The noun delusion is often used in the phrase delusions of grandeur, which expresses the belief that unattainable goals are well within reach, like a terrible actress's delusions of grandeur that she won't just land her first role in a movie, it also will make her an Academy Award winner. Delusions like that can be amusing for onlookers, but other kinds of delusions are not, like those suffered by the mentally ill. Their delusions can remove them from reality, making it hard to function.

Definitions of delusion

n a mistaken or unfounded opinion or idea

“he has delusions of competence”
disorientation, freak out
a wild delusion (especially one induced by a hallucinogenic drug)
Type of:
an incorrect conception

n the act of deluding; deception by creating illusory ideas

head game, illusion
Type of:
deceit, deception, dissembling, dissimulation
the act of deceiving

n (psychology) an erroneous belief that is held in the face of evidence to the contrary

psychotic belief
show 9 types...
hide 9 types...
delusions of grandeur
a delusion (common in paranoia) that you are much greater and more powerful and influential than you really are
delusions of persecution
a delusion (common in paranoia) that others are out to get you and frustrate and embarrass you or inflict suffering on you; a complicated conspiracy is frequently imagined
illusory perception; a common symptom of severe mental disorder
nihilism, nihilistic delusion
the delusion that things (or everything, including the self) do not exist; a sense that everything is unreal
somatic delusion
a delusion concerning the body image or parts of the body
the delusion that you have assumed the form of an animal
acousma, auditory hallucination
illusory auditory perception of strange nonverbal sounds
an image vivid enough to be a hallucination but recognized as unreal
visual hallucination
illusory visual perception
Type of:
mental condition, mental state, psychological condition, psychological state
(psychology) a mental condition in which the qualities of a state are relatively constant even though the state itself may be dynamic

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