An allusion is a brief and indirect reference to a person, place, thing, or idea of historical, cultural, literary, or religious significance. It's like a wink to the reader, expecting them to recognize the reference and make a connection to the original work.
Here's an example:
* "He was a real Romeo with the ladies." This alludes to the character Romeo from Shakespeare's play, *Romeo and Juliet*, known for his romantic nature.
By understanding the allusion, the reader can add layers of meaning and understanding to the text.