Illusion n. : An unreal image presented to the bodily or mental vision; a deceptive appearance; a false show; mockery; hallucination.

Illusion n. : Hence: Anything agreeably fascinating and charning; enchantment; witchery; glamour.

Illusion n. : A sensation originated by some external object, but so modified as in any way to lead to an erroneous perception; as when the rolling of a wagon is mistaken for thunder.

Illusion n. : A plain, delicate lace, usually of silk, used for veils, scarfs, dresses, etc.

Example:
Can color create the Illusion of depth without the Illusion of transparency?

Taxonomy
illusion, optical illusion, philosophy, the brain, visual illusions, assumptions, truth, falsehood, free encyclopedia, distortion, human senses, Auditory illusions, taste, Maya, Hindu philosophy, stimulus, dummy, hearing voices.

Defination from the web:
... a distortion in the absence of a stimulus, an illusion describes a misinterpretation of a true sensation. ... An optical illusion is always characterized by visually perceived images that, at least in common sense terms, are deceptive or misleading. ... Main article: Auditory illusion ...