2. A discrepancy between the expected and actual state of affairs.
– Canadian Oxford Dictionary, 1998<O:P> </O:P>

3. A condition of affairs or events exactly the reverse of what was expected: the irony of fate. – New International Webster’s Dictionary and Thesaurus, 2000

4. Irony of Fate: Fate’s mock compliance with one’s wishes, e.g., water everywhere, nor any drop to drink. – Pocket Oxford Dictionary (UK revised 4^th edition, 1946)

5. A condition in which one seems to be mocked by fate or the facts.
– The Chambers Dictionary, 1998

6. And the double audience for the irony of Fate? Nature persuades most of us that the course of events is within wide limits foreseeable, that things will follow their usual course, that violent outrage on our sense of the probable or reasonable need not be looked for; and these ‘most of us’ are the uncomprehending outsiders; the elect or inner circle with whom Fate shares her amusement at our consternation are the few to whom it is not an occasional maxim, but a living conviction, that what happens is the unexpected. – A Dictionary of Modern English Usage, by H. W. Fowler (1^st edition, 1926)

7. Situation, event etc., that is desirable in itself but so unexpected or ill-timed that it appears to be deliberately perverse: the irony of fate. He inherited a fortune but died a month later; one of life’s little ironies.
– Oxford Learner’s Dictionary of Current English, Encyclopedic Edition, 1992

8. Ill-timed or perverse arrival of event or circumstance in itself desirable, as though in mockery of the fitness of things. – Concise Oxford Dictionary (UK 6^th edition, 1976)

9. An ill-timed or perverse arrival of an event or circumstance that is in itself desirable.
– Concise Oxford Dictionary (UK 8^th edition, 1990)

10. The quality of an occurrence being so unexpected or ill-timed that it appears to be deliberately perverse. – Oxford Paperback Dictionary (4^th edition, 1994)

11. Apparent perversity of fate or circumstances. – Oxford Guide To The English Language (1984)

12. cosmic irony/irony of fate -- when a malicious force seems to deliberately frustrate human efforts.
 

Concise Oxford Dictionary, 8^th edition:

1 an expression of meaning, often humorous or sarcastic, by the use of language of a different or opposite tendency.
2 an ill-timed or perverse arrival of an event or circumstance that is in itself desirable.
3 the use of language with one meaning for a privileged audience and another for those addressed or concerned. [L ironia f. Gk eironeia simulated ignorance f. eiron dissembler]

http://www.brown.edu/Student_Services/Writing_Center/halpern1.htm

Recognizing Irony

http://xroads.virginia.edu/~DRBR/woodward.html

The Irony Of Southern History