Noun

1. Anything that seems to be something that it is not.
   • We saw what looked like a tiger among the trees, but it was an illusion caused by the shadows of the branches.
   • Using artificial additives, scientists can create the illusion of fruit flavours in food.
2. A misapprehension; a belief in something that is in fact not true.
   • Jane has this illusion that John is in love with her.
3. A magician’s trick.
4. The fact of being an illusion (in any of the above senses).

Etymology