Illusion is a term that refers to something that appears to be true but is actually false. There are several synonyms for this term that can be used to describe an illusion. One of the synonymous terms is mirage, which is a phenomenon where objects appear closer or farther away than they actually are due to the bending of light. Another synonym for illusion is hallucination, which refers to a perception of something that does not exist in reality. The term delusion is also synonymous with illusion, which refers to a false belief or idea held firmly by a person despite evidence to the contrary. Other synonyms of illusion include apparition, phantasm, and chimera.