Irony - Using the word properly

I realize this may seem rather picky, but it's a common error of language that I find really irritating. Watching the evening news today I was amazed to hear one of the broadcasters misuse the word irony. It's a very common error but a newscaster should know better. Many people use the word irony when they should be using the word unusual, or perhaps interesting, but certainly not irony. According to The American Heritage Dictionary of the English Language the meaning of irony is the use of words to express something different from and opposite to their literal meaning. Irony does not mean unusual; it means opposite. Steve Martin was right when, in the movie Roxanne, he said that nobody gets irony any more.