1. using words to convey a meaning that is the opposite of its literal meaning; containing or exemplifying irony an ironic novel; an ironic remark.
2. of, pertaining to, or tending to use irony or mockery; ironical
3. coincidental; unexpected: It was ironic that I was seated next to my ex-husband at the dinner.
People misuse this word all the damn time. Notably, and to my eternal annoyance, Alanis Morissette; her contribution to propagating the misapplication of the term deserves, at least, a sound flogging. She’s Canadian and thus properly educated. She should know better.
I had a particularly vexing encounter with abusage of the word just last night. Someone who was displeased I was not paying him the attention he felt he deserved ended the expression of said displeasure with:
“That’s what I call ironic.”
Now, that they believed I was somehow obliged to respond at all, let alone in any particular fashion was bothersome in itself, but that he went on to call my lack of response ironic provoked me to actual crankiness. 
It turns out that irony has a specific threshold of meaning. Despite rampant misconception about the matter it doesn’t simply mean something you find irksome or disappointing. There must be some twist which ties the occurrence back to something else.
For example, if instead I had been pursuing this person relentlessly and finally garnered a response which I then ignored, that would indeed be ironic. Defying his expectation that I would or should respond absent any other influence was simply unsatisfying. Not, in fact, ironic.
And boys, you wanna hang with me? Gird your loins and grab a dictionary. You’ll fare better thereby.