On some WikiForums, a keyword added to a WikiPage to help classify pages. It is a WikiWord keyword, prefixed by "Category", like (on CLUG) "CategoryLvlug?". Usually, a WikiPage with the WikiWord keyword as title is created to serve as an aid to finding the pages in that category. By going to that page and clicking on the title, you can find all the WikiPages which include that keyword. See also Topic, which is very similar. At one point a distinction between Topic and Category was intended, but that has not always been achieved in practice. See FaqForCategories and related pages.
wiki
An informal general term that might refer to a WikiEngine, a WikiForum, or the combination of the two, but not a WikiFarm or a WikiSite). I will use it in general discussion or when I think the precise reference is clear from the context.
The software running a WikiForum. Sometimes referring to just the "custom written" stuff, sometimes including the infrastructure, like the database and webserver.
All or a collection of many WikiForums, perhaps with InterWiki links connecting individual pages from one wiki to pages in another wiki. (I'm not sure how many people will agree with this definition. I've sensed that other people sometimes use WikiWeb to refer to what I call a WikiForum.)
The following is quoted from a page I added at the TWiki forum (http://twiki.sourceforge.net/cgi-bin/view/TWiki/TWikiSubWeb), trying to explain their concept of multiple webs within a wiki. Once I let it "settle out", I may modify other definitions on this page as appropriate to be consistent with the following.
A wiki forum is a web site where a (an instance of a) wiki engine supports a set of wiki pages. A wiki farm is a web site where multiple instances of a wiki engine each support a set of wiki pages (or, possibly, multiple wiki engines each support a set of wiki pages). TWiki allows one instance of a wiki engine to support multiple sets of wiki pages, with some functions (for example, search) common to all sets of pages. (See http://www.c2.com/cgi/wiki?WikiForum, http://www.c2.com/cgi/wiki?WikiFarm, and http://www.c2.com/cgi/wiki?WikiEngineReviewTerminology .)
Or, maybe, a wiki farm is a web site with multiple independent sets of wiki pages. (And, a set of wiki pages is a WikiForum.)
An "artificial" word, usually formed by scrunching two or more capitalized words together, and used as the title of a WikiPage or WikiTopic? discussing a subject represented by the WikiWord. WikiWord is a WikiWord.