An Illusion

1. (countable) Anything that seems to be something that it is not.
2. (countable) A misapprehension; a belief in something that is in fact not true.
3. (countable) A magician’s trick.
4. (uncountable) The state of being deceived or misled.

Synonyms

• (that seems to be something it is not): mirage, phantom
• (a belief in something untrue; the state of being misled): delusion
• (a belief in something untrue): misapprehension, misbelief, misconception