Irony is a subtle figure of speech in which, while one thing is said, some indication serves to show that quite the opposite is meant; thus apparent praise becomes severe condemnation or ridicule; practical irony is evinced in ostensibly furthering some one's hopes and wishes while really leading him to his overthrow. Life and history are full of irony in the contrast between ambitions and their realisation.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Ironsides * Irony, Socratic