Allusion:
noun
noun
- an expression designed to call something to mind without mentioning it explicitly; an indirect or passing reference.
"an allusion to Shakespeare"
Therefore, an allusion is when a piece of writing tries to hint at a person, place, thing, literature, or art. An allusion is when we hint at something and expect the other person to understand what we are referencing. For example: Chocolate is his Kryptonite.

