What is a literary device called, in which real meaning is concealed or contradicted?

Irony (from Ancient Greek εἰρωνεία eirōneía 'dissimulation, feigned ignorance'), in its broadest sense, is a rhetorical device, literary technique, or event in which what on the surface appears to be the case or to be expected differs radically from what is actually the case.

Irony can be categorized into different types, including verbal irony, dramatic irony, and situational irony. 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.