Defining "midlife crisis."

We're having a little debate here about the meaning of "midlife crisis." Here's the Wikipedia definition to get you started:

A mid-life crisis is an emotional state of doubt and anxiety in which a person becomes uncomfortable with the realization that life is halfway over. It commonly involves reflection on what the individual has done with his life up to that point, often with feelings that not enough was accomplished. The individual may feel boredom with their lives, jobs, or their partners, and may feel a strong desire to make changes in these areas. The condition is also called the beginning individuation, a process of self-actualization that continues on to death. The condition is most common in people in their 30s and 40s, and affects men more often than women.

Clearly, that definition needs some tweaking, but what do you think? Is this a useful term to an individual reflecting on his or her own life? Do you feel better or worse or different about your situation if someone characterizes it as a "midlife crisis"?

Here's something I wrote in the course of this little local debate I'm referring to:

I think the MLC is when you are married and living complacently and then you start taking risks violating conventions because you don't want to be that kind of person anymore. Once you're out of the marriage, the crisis is over. You're just adapting to new conditions in a normal way. Having problems and bad feelings is normal life, not a crisis.

What do you think?

UPDATE: Terry Teachout takes "midlife crisis" to have a broader and more serious meaning than I do, which will please at least one participant in the local debate I've alluded to. I take the feeling he describes seriously, but I still don't like the term "mid-life crisis" for it. The term has an unserious tone to my ear, like the old "identity crisis." Teachout's concern is confronting the reality of death, however, and the person I have been debating with locally is chafing at the inadequacies and boredom of ordinary life. My local interlocutor wants to break out and change all sorts of things (but is not doing anything very unsual), and Teachout is talking about coming to terms with a reality that he has zero potential to change. The similarity is a feeling of wanting to live -- in some fuller way than seems currently available.