Yes, nice term. What does it mean? Within philosophy, analytic philosophy in particular, definition is an important part of the game. For example, defining the question, as I discussed in my last post, is a very important task. "Metaethics," is the field within philosophy that aims to "define the question" of ethics. It asks questions like "What is morality in the first place," "Generally speaking, what makes an action wrong or right," "Is morality absolute?"
For example, our culture tends to have three metaethical theories in mind when it talks about morality. The first, the one you usually see associated with conservatives. Wrong and right are objective features of the world, written laws in some book. For every moral question, there is a definite answer. It is, on this view, our duty to follow the law.
In contrast to this, there's a utilitarianism, by way of some muddled existentialism and romanticism, that holds that what is right is tied into happiness - specifically the greatest happiness for the greatest number. This usually takes some form of the maxim "do what you want as long as it doesn't hurt others" - though often phrased in more nuanced ways. This view is usually also mixed in with a relativism that holds morality to have no absolutes. Of course, that isn't necessarily the case, and most hold at least the "no harm" maxim to be an absolute.
Finally, there's those out there who are simply metaethical nihilists. There is no morality, no right and wrong, not even any harm principle. One make act morally, but it's simply out of convenience.
Unfortunately, the fact that most people don't think about metaethics can also lead to a lot of confusion. Those in the first category, for example, will often confuse those who hold to the harm principle with nihilists, thinking them to literally have no morals.
And actually, those in the second camp sometimes make a similar mistake. Namely, they come to think that morality is only what the other side is talking about - a code of specific rights and wrongs, and they conclude that that's really a matter of personal choice (thus "morality is a matter of personal choice"). The actual utilitarian morality they hold to isn't thought by them to be morality at all, but simply a fact.
There are actually been quite a few other metaethical theories of importance, among them contractualism and virtue ethics. The latter of the two may actually get discussion in an upcoming post, because it's at the very least historically important. For now though, I just wanted to outline the field of metaethics, and lay out what seem to be the two most dominate views today. I also hope this might get you thinking about what metaethical assumptions you might be making - both about yourself and about those with whom you disagree.