Definition of "illusion" in English

noun

1. (countable) 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. (countable) A misapprehension; a belief in something that is in fact not true.

   • Jane has this illusion that John is in love with her.

3. (countable) A magician’s trick.

4. (uncountable) The state of being deceived or misled.