It appears to me that freedom is first mentioned in the Fourth Meditation when the meditator first states that her errors depend on knowledge and "the faculty of choice or freedom of the will". Here is seems the most simple definition of freedom is choice. In fact later, after she discusses the faculty of knowledge she switches the terms in saying "the will, or freedom of choice". Thus, I think it is safe to say that freedom in this case is interchangeably freedom of choice or freedom of the will.

The tricky part is decifering what this means. This freedom of choice in the will turns out to be the greatest faculty the meditator can conceive of and thus because of the will that she considers herself to bear some likeness to God. Although God's will is greater due to knowledge power and object of the will, the meditator sees the will as simply the "ability to do or not do something (that is, to affirm or deny, to pursue or avoid)". Take an apple: one may affirm its juiciness or deny it, one may eat it or not eat it, one may pursue it by going towards it to partake of it or avoid it because maybe one's seen too many still lifes and it creeps him or her out. From here it seems that freedom is found in the will and the will is the ability to do or not do something, so given an object or a situation or an idea or whatever, freedom is the ability to do whatever with it.

Of course it is not that simple as the meditator lays out degrees of freedom (in the non-statistical sense). She goes on to explain the will further stating that "when the intellect puts somethin forward...our inclinations are such that we do not feel we are determined by any external force". Given that, the meditator continues stating that to be free does not mean we need to inclined both ways. In fact, and here's the tricky part, if we are inclined one way "the freer is my choice". Divine gracea and natural knowledge apparently only increase and strengthen freedom. Further, indifference in a choice is the lowest grade of freedom. If the meditator always saw what was true and good, she would be "wholly free" because she would never feel indifference.

So let's break that down. Indifference is the lowest grade of freedom. This makes sense to a degree to me because if we are indifferent about something than we won't utilize our freedom really, or if we do there's no passion or cause behind it. Some people may be indifferent towards say playing a sport. They don't really care either way, so they just play because whatever. Whereas, there may be people out there who want nothing more than to play a sport and they play because they are inclined to and they are really utilizing their freedom, it seems a higher form of freedom to me somehow. Most see the fact that higher freedom is when one is divinely inspired to be a form of determinism. Wholly free as always being told what is true and good seems to leave out the choice. However, I think it's really just a negation of relativism. If we are say divinely inspired or just always know what is true and good, well that may incline us one way, but for some it could still incline them the other way. We still have the choice to do or not do, we still have our will. We just happen to know what a true and good choice is. However, since we are finite and imperfect we are capable of deceit and wanting to do what isn't good and true. We've all done things we knew ahead of time weren't the best things. Just because we are given the knowledge does not mean we are forced to do anything. The fact that we have the knowledge makes us freer because when we utilize our will we know what we're getting ourselves into either way and we aren't just making a blind choice.