Well, the best way to define "theistic evolution" is basically: it is what theistic evolutionists believe.
That may seem like sort of a roundabout but you have to remember that beliefs don't exist in some sort of philosophical aether independent of real people. And anyways, I'm about to go into what a theistic evolutionist is.
The simplest definition of a "theistic evolutionist" is simply someone who both believes in theism (that is, the existence of God and His active participatory involvement in creation, whether by natural sustenance or supernatural gestures) - in the context of this forum and the general cr-evo debate normally a Christian theist - and accepts that biological evolution, along with other conventional theories which creationists deny, is the best current scientific explanation for the data we have at hand.
Note that it is inherently a reactionary definition, and sometimes we rant about that. Nobody, after all, ever has to identify themselves as a "theistic gravitationalist" or a "theistic relativist" (in the sense of general and special relativity, not moral relativity). So why "theistic evolutionist"? Well, because creationists have created a social controversy by stating that evolution is both scientifically and morally wrong. (I am assuming you are familiar or at least aware of this - being an Aussie like me, you should be!) As such, the label "evolutionist" automatically carries notions of atheism to the creationist, forcing us to label ourselves "theistic evolutionists" - just as: if a large group of Christians considered gravity to be a figment of what atheists believe, then we who believed that gravity exists would have to qualify that we are "theistic gravitationalists" to separate ourselves from those who aren't.
Is it another term for "Intelligent Design"? On one level, a theistic evolutionist (here at least) is a Christian, and most Christians (certainly all I've seen here) believe that God indeed did design the universe in the teleological, philosophical, spiritual and moral senses. In that sense we are indeed "intelligent design" advocates and on these grounds we have been criticized by atheists before. But we do not believe this in the scientific sense that the ID movement puts forth. Many ID advocates (and indeed creationists themselves, when arguing about scientific points non-essential to their views) agree with evolutionary theory to some extent. Michael Behe himself has confessed to not seeing any difficulty in common descent - as long as organelles and DNA are intelligently designed. However, what separates them from theistic evolutionists is the general difference in our outlook on science. A quote by William Dembski demonstrates this:
"I think at a fundamental level, in terms of what drives me in this is that I think God's glory is being robbed by these naturalistic approaches to biological evolution, creation, the origin of the world, the origin of biological complexity and diversity. When you are attributing the wonders of nature to these mindless material mechanisms, God's glory is getting robbed. [...] And so there is a cultural war here. Ultimately I want to see God get the credit for what he's done - and he's not getting it."
("The design revolution?" TalkReason.org 2004)
An ID advocate (and a creationist in general) would see a God of the gaps, a God who is glorified when people can't figure out what He has done. By contrast, a central feature of theistic evolution (which may be articulated in different ways by different evolutionists here) is that naturalistic approaches to God's creation actually reveal even more of His glory instead of robbing it. Even though outwardly IDists my yield to some evolutionary conclusions, the philosophical innards are completely different.
One last thing: "theistic evolution" is indeed an ugly phrase, and it's not a moniker I'm proud of. And in some way I'm glad you've never heard of it. Nobody needs to confess to being a theistic heliocentrist, or a theistic gravitist, or a theistic quantum-mechanicist. It shows that we've grown so comfortable with these physical theories that we take it for granted that a Christian can accept gravity and heliocentricity without jeopardizing their Christian-ness. But "I'm a Christian, theistic evolutionist" is typically the answer to a suspicious, paranoid, there's-wool-but-is-a-wolf-under-it? question: "So you're an evolutionist ... but you're still a Christian? How does that work?"
Yes, that is what we theistic evolutionists are: Christians who accept evolution. But we're not proud of the fact that we have to declare ourselves as such.
