Allusion

[3] When a connection is directly and explicitly explained (as opposed to indirectly implied), it is instead often simply termed a reference.

[7] In a wider, more informal context, an allusion is a passing or casually short statement indicating broader meaning.

Allusion is an economical device, a figure of speech that uses a relatively short space to draw upon the ready stock of ideas, cultural memes or emotion already associated with a topic.

Thus, an allusion is understandable only to those with prior knowledge of the covert reference in question, a mark of their cultural literacy.

Martin Luther King Jr., alluded to the Gettysburg Address in starting his "I Have a Dream" speech by saying "Five score years ago..."; his hearers were immediately reminded of Abraham Lincoln's "Four score and seven years ago", which opened the Gettysburg Address.

King's allusion effectively called up parallels in two historic moments without overwhelming his speech with details.

The activation is achieved through the manipulation of a special signal: a sign (simple or complex) in a given text characterized by an additional larger "referent."

The "free" nature of the intertextual patterns is the feature by which it would be possible to distinguish between the literary allusion and other closely related text-linking devices, such as parody and pastiche.