Irony (from Ancient Greek εἰρωνεία (eirōneía), meaning 'dissimulation, feigned ignorance'), in its broadest sense, is a rhetorical device, literary technique, or event in which what appears, on the surface, to be the case, differs radically from what is actually the case. Irony may be divided into categories such as verbal, dramatic, and situational.
Verbal, dramatic, and situational irony are often used for emphasis in the assertion of a truth. The ironic form of simile, used in sarcasm, and some forms of litotes can emphasize one's meaning by the deliberate use of language which states the opposite of the truth, denies the contrary of the truth, or drastically and obviously understates a factual connection.
Other forms, as identified by historian Connop Thirlwall, include dialectic and practical irony.
Henry Watson Fowler, in The King's English, says, "any definition of irony—though hundreds might be given, and very few of them would be accepted—must include this, that the surface meaning and the underlying meaning of what is said are not the same." Also, Eric Partridge, in Usage and Abusage, writes that "Irony consists in stating the contrary of what is meant."
The use of irony may require the concept of a double audience. Fowler's A Dictionary of Modern English Usage says:
Irony is a form of utterance that postulates a double audience, consisting of one party that hearing shall hear & shall not understand, & another party that, when more is meant than meets the ear, is aware both of that more & of the outsiders' incomprehension.
The term is sometimes used as a synonym for incongruous and applied to "every trivial oddity" in situations where there is no double audience. An example of such usage is: