Dramatic irony arises when an audience experiences a discrepancy between its view of the play and the understanding of the characters on stage. This discrepancy is usually a function of plot, as in Shakespeare's Romeo and Juliet when the audience knows that Juliet has taken a sleeping potion in order to seem dead, but Romeo does not know this and commits suicide beside her seeming corpse. This moment in Romeo and Juliet is based on the story of Pyramus and Thisbe from Ovid's Metamorphoses (written around 5-10CE), but such dramatic irony is older still: in Sophocles' play Oedipus the King (circa 420BCE), when King Oedipus proclaims that whoever has angered the Gods and brought terrible afflictions on the city …
Editors. "Dramatic Irony". The Literary Encyclopedia. First published 01 November 2002; last revised 30 November -1.
[http://www.litencyc.com/php/stopics.php?rec=true&UID=574, accessed 21 April 2015.]