illusion, semblance (noun)

an erroneous mental representation

illusion, fantasy, phantasy, fancy (noun)

something many people believe that is false

"they have the illusion that I am very wealthy"

delusion, illusion, head game (noun)

the act of deluding; deception by creating illusory ideas

magic trick, conjuring trick, trick, magic, legerdemain, conjuration, thaumaturgy, illusion, deception (noun)

an illusory feat; considered magical by naive observers

illusion (Noun)

Anything that seems to be something that it is not.

illusion (Noun)

A misapprehension; a belief in something that is in fact not true.

illusion (Noun)

A magician's trick.

illusion (Noun)

The fact of being an illusion (in any of the above senses).

Illusion

An illusion is a distortion of the senses, revealing how the brain normally organizes and interprets sensory stimulation. While illusions distort reality, they are generally shared by most people. Illusions may occur with more of the human senses than vision, but visual illusions, optical illusions, are the most well known and understood. The emphasis on visual illusions occurs because vision often dominates the other senses. For example, individuals watching a ventriloquist will perceive the voice is coming from the dummy since they are able to see the dummy mouth the words. Some illusions are based on general assumptions the brain makes during perception. These assumptions are made using organizational principles, like Gestalt, an individual's ability of depth perception and motion perception, and perceptual constancy. Other illusions occur because of biological sensory structures within the human body or conditions outside of the body within one’s physical environment. The term illusion refers to a specific form of sensory distortion. Unlike a hallucination, which is a distortion in the absence of a stimulus, an illusion describes a misinterpretation of a true sensation. For example, hearing voices regardless of the environment would be a hallucination, whereas hearing voices in the sound of running water would be an illusion.