From Longman Dictionary of Contemporary Englishoptical illusionˌoptical ilˈlusion noun [countable] HPOTRICK/DECEIVEa picture or image that tricks your eyes and makes you see something that is not actually there
Examples from the Corpus
optical illusion• Even better, the full Coliseum will not be an optical illusion.• This is called an optical illusion, which means that your eyes trick you into seeing something that is not really there.• This is an optical illusion in which the diagram of a skeleton cube appears to the observer in either of two orientations.• Shiseido's Wrinkle Smoothing Concentrate works on the principle of an optical illusion.• It was probably an optical illusion, but the place seemed to be flying more eagles and swastikas than stars and stripes.• Even knowing what he did, Kirov found it difficult to see how the optical illusion had been managed.• For once, the optical illusion experienced by sailors leaving port seemed apt. 