“Allusion: Usually an implicit reference, perhaps to another work of literature or art, to a person or an event. It is often a kind of appeal to a reader to share some experience with the writer. An allusion may enrich the work by association (q.v.) and give it depth. When using allusions a writer tends to assume an established literary tradition, a body of common knowledge with an audience sharing that tradition and an ability on the part of the audience to ‘pick up’ the reference. The following kinds may be roughly distinguished: (a) a reference to events or people (e.g. there are a number in Dryden’s and Pope’s satires); (b) reference to facts about the author himself (e.g. Shakespeare’s puns on Will; Donne’s puns on Donne, Anne, and Undone; (c) a metaphorical allusion (there are many in T.S. Eliot’s work); an imitative allusion (e.g. Johnson’s to Juvenal in London).”
Excerpted from: Cuddon, J.A. The Penguin Dictionary of Literary Terms and Literary Theory. New York: Penguin, 1992.