An optical illusion is an illusion caused by the visual system and characterized by visually perceived images that differ from objective reality. The three crossword solutions for the term optical illusion are MIRAGE (6 letters), TRICK (5 letters), and TRICE (5 letters). MIRAGE is an optical illusion caused by atmospheric conditions, where distant objects appear to be displaced or hazy. TRICK is an act intended to deceive or outwit someone. TRICE is an archaic term meaning a very short space of time.