What do we mean by "liberal" or "conservative"?

The answer may depend on the speaker, but one of the most balanced and thoughtful explications that I have seen is in this post by Keith Burgess-Jackson (also known for his less balanced blog, AnalPhilosopher). I really like the whole thing, but perhaps a representative pullquote would be this:

Liberals look forward, believing that peace, justice, and happiness are just around the corner, if only we let reason be our guide. Conservatives look backward, believing that if we tinker with tradition, even with the best of intentions, we are as likely to get war, injustice, and misery as their opposites.

Not a bad crystallization of how people with good intentions can differ so markedly in their sense of where to go next. But the longer descriptions are better. Worth a read.