Irony
The essence of irony consists in the foregrounding not of the logical but of the evaluative meaning. The context is arranged so that the qualifying word in irony reverses the direction of the evaluation, and the word positively charged is understood as a negative qualification and (much-much rarer) vice versa.
Irony thus is a stylistic device in which the contextual evaluative meaning of a word is directly opposite to its dictionary meaning. So, like alt other SDs irony does not exist outside the context, which varies from the minimal-a word combination, as in J. Steinbeck's "She turned with the sweet smile of an alligator," - to the context of a whole book, as in Ch. Dickens, where one of the remarks of Mr. Micawber, known for his complex, highly bookish and elaborate style of speaking about the most trivial things, is introduced by the author's words "...Mr. Micawber said in his usual plain manner".
In both examples the words "sweet" and "plain" reverse their positive meaning into the negative one due to the context, micro- in the first, macro- in the second case.
In the stylistic device of irony it is always possible to indicate the exact word whose contextual meaning diametrically opposes its dictionary meaning. This is why this type of irony is called verbal irony.
There are very many cases, though, which we regard as irony, intuitively feeling the reversal of the evaluation, but unable to put our finger on the exact word in whose meaning we can trace the contradiction between the said and the implied. The effect of irony in such cases is created by a number of statements, by the whole of the text. This type of irony is called sustained, and it is formed by the contradiction of the speaker's (writer's) considerations and the generally accepted moral and ethical codes. Many examples of sustained irony are supplied by D. Defoe, J. Swift, by such contemporary writers as S. Lewis, K. Vonnegut, E. Waugh and others. "It must be delightful to find oneself in a foreign country without a penny in one's pocket."