Definition of: illusion

(i·l′zhən) noun
1. An unreal image seemingly presented to the senses; any misleading appearance; a false show.
2. Psychol. A sensory impression which misrepresents the true character of the object perceived; false perception. See HALLUCINATION.
3. The act of deceiving or misleading by a false appearance.
4. The state of being deceived; delusion; false impression.
5. A thin material resembling tulle, usually of silk: used for veils and garments.
6. An artistic effect giving the appearance of reality to a painting. See synonyms under DELUSION, DREAM. [<OF <L illusio, -onis mocking, deceit <illudere make sport of. See ILLUDE.]
—il·lu′sion·al adjective