Vote for the answer!
There is a Wiki called Braindumps, and they specialize in test answers. What's so awesome about thier Wiki, is that users VOTE for the correctness of an answer. So if one person writes; A plasma is a bunch of hot air, and another writes A plasma is " Physics. An electrically neutral, highly ionized gas composed of ions, electrons, and neutral particles. It is a phase of matter distinct from solids, liquids, and normal gases.", from dictionary.com In this fashion, it's very difficult for an incorrect answer to pass the test of time. It also allows them to be appended with new information, and the reader gets to choose, which answer to accept as understandable truth.