, Fecal matter.

Also, I think materia is a brilliant name for it. It sounds like "material" but by dropping the L, it gives it a mystical sort of sound. It really fits in well with the world. That is, mysticsm, mythology, and magic in a highly realized technological world. They take the word "material" and give it an enigmatic edge. Since most people don't even know what materia really is, it's fitting in that sense as well.

All of this goes back to Sephiroth's explanation of materia in the Mt. Nibel flashback. It let's you cast magic, but in such a scientific world, using a wod like magic would be scoffed at. The word materia itself can mimic the passing of the Ancients from the world, but more importantly from common knowledge. In a technological world, everything can be explained by science. Magic, spiritualism, and cosmology are things people no longer have respect for, or believe in.