Definition of illusion

The origin of the word "illusion" can be traced back to the Old French noun "illusioun" which meant "delusion" or "mistaken belief". This word was derived from the Latin noun "illusio" which carried a similar meaning. In the 14th century, the Middle English adopted "illusion" from French and the spelling gradually changed to the modern form. The word initially referred to any false belief or deception, whether natural or supernatural, as in the illusions of demons or magicians. The modern meaning of "illusion" as a perceived reality that is actually false, often resulting from sensory deception, can be traced back to the 18th century. This sense hasimbued new meanings for the word, such as its usage in the arts to refer to visual, auditory, or first-person experiences that appear real but aren't, and its application in science and psychology to describe observed phenomena that later turn out to be erroneous or incomplete.