noun
1. something that deceives by producing a false or misleading impression of reality.
2. the state or condition of being deceived; misapprehension.
3. an instance of being deceived.
4. Psychology. a perception, as of visual stimuli (optical illusion), that represents what is perceived in a way different from the way it is in reality.
illusion is a distortion of the senses, revealing how the brain normally organizes and interprets sensory stimulation.
"An illusion here may be defined, with A.D. Smith, as “any perceptual situation in which a physical object is actually perceived, but in which that object perceptually appears other than it really is” (Smith 2002: 23). For example, a white wall in yellow light can look yellow; a sweet drink can taste sour if one has just eaten something sweeter; a quiet sound can seem loud if it is very close to you; and so on. In these cases it is not necessary that one is deceived into believing that things are other than they are; so illusion in this sense need not involve deception. One can know that one is experiencing an illusion when it is happening."
- Stanford Encyclopedia of Philosophy
