Irony (from Ancient Greek, 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 the simile, used in sarcasm, and some forms of litotes can emphasize one’s meaning by the deliberate use of the 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 the historian Connop Thirlwall, include dialectic and practical irony.

https://en.wikipedia.org/wiki/Irony