I agree that inventive, one-use terms needn't be put on the wiki. (I wouldn't put my definition of rationality up because I have little or no knowledge of the group think -- I just wanted to get the conversation started). But if someone puts effort into defining a term accurately (for example a term that is gaining currency), especially in a way that is a good summary of how the group in general tends to understand it, they should add it the Wiki. Defining terms is important but might take a lot of work.