Irony (noun)

1. A situation in which actions or events are opposite to what is expected or what appears to be appropriate.
2. A quality of speech or writing that suggests a meaning that is opposite or very different from the literal or usual meaning of the words used.

Origin:

From old french ironie, from latin ironia, from ancient greek εἰρωνεία (eirōneía), from εἰρωνεύς (eirōneús), 'dissimulating, feigning ignorance'.

Examples:

1. The irony of losing my job on the day I was given a bonus was not lost on me.
2. The irony of the situation was that the fire station burned down.
3. The irony of life is that it can be both beautiful and cruel at the same time.
4. The speaker's use of irony emphasized the absurdity of the situation.
5. It was ironical that the man who had always preached non-violence was killed in a violent way.