This page is for those of you who may be scratching your heads and asking what ships have to do with stories, and just what the heck is a "plot bunny," anyway? I will hopefully be adding to the glossary periodically, as I get time, but this listing should at least get you started.
As the name implies, fanfiction means a story written by a fan. Fanfiction might be written about a TV show, a film, a published book or book series, a video game, and so on using the same universe and often the same characters as the original media. There are sometimes copyright issues with the actual author of said media, or with the company who owns the rights to it, and attitudes vary a lot; some forbid any fanfiction at all, others allow it only within the aegis of a licenced fan club or similar organization, and still others have essentially opened the playing field to anyone who wants to be involved. It's very, very rare for anyone to get paid for writing fanfiction, however--most often, it's written and "published" (usually via the internet) just for fun.
The word "fanfiction" is often shortened to "fanfic."
This refers to a particular "universe" about which fanfic is written, and also to the usually loose and informal communities of people who are fans of a particular book series, movie, etc.
A shorthand term for an individual story.
A term that I first encountered in the Harry Potter fandom, a plot bunny is essentially an idea, either for an entire story or for a situation that might well generate a larger story. The etymology is uncertain, but may spring from a quote by John Steinbeck that says ideas are like rabbits; you get one or two at first, and then suddenly you have dozens. (They're also occasionally called "plot daemons," but I like bunnies better--they're much cuter than daemons. )
In software testing, a "beta tester" is someone who takes a nearly finished program and fiddles with it in every way they can think of to find (and fix) as many bugs as they can before the program goes to an actual public release. Beta-readers, then, do much the same thing for fanfiction; they read over drafts of individual fics to help find typos and grammatical errors, and usually offer suggestions on how to improve the story itself. It's not strictly necessary to have a beta-reader to write fanfiction, or even to have it published--but all the best fics I've ever read have been beta-read not just once but multiple times, and personally, I think a good beta-reader is a resource that no serious fanfic writer can afford to be without...
A term that refers to the "rules" for a particular universe which have been set down in the original book, film, etc. about which fanfiction is written. Fanfic, by its very nature, invites speculation on aspects of the original universe that the author either gives no information about or only hints at, and so most fanfic authors have to strike a balance between staying true to canon and using their own ideas or extrapolations.
An acronym which stands for "Original Character." This refers to characters which are invented by the fanfic author and don't appear in canon. OC's are sometimes viewed with a certain amount of suspicion by the readers of fanfic, due mainly to the fact that it takes some skill at writing to really pull them off properly, and--as with many aspects of fiction, fan and otherwise--done badly, they're absolutely dreadful. A related (and rather derogatory) term is "Mary Sue" (along with her less-common male counterpart, "Gary Stu"); this references a particular type of badly-written OC. "Mary Sues" are usually lacking in human flaws, resemble their author, and often end up romantically involved with whichever canon character the author has a crush on. I'm personally of the opinion that it's quite possible to write oneself into a fic and/or live out a bit of a fantasy with a favorite character without necessarily straying into Mary Sue territory, but it does take a certain amount of care and a healthy dose of objectivity about one's own work.
One of the most popular aspects of fanfic is the opportunity to explore romantic interactions between characters within a particular fandom. Occasionally such a romance was explicitly spelled out in the original book or film, but oftentimes it is purely speculative. "Ship" is short for "relationship," and refers to a particular pairing of characters in this manner, usually described as Character A/Character B. People who favor such a pairing are called "shippers," and the term can be used as a verb as well as a noun; people who like a particular pairing are said to "ship it."
A subgenre that stretches across many different fandoms, slash is a kind of umbrella term applied to fanfic that involves homosexual relationships between characters. It's also quite popular; there are dozens of online communities devoted to it.
My own personal interest in slash is lukewarm at best--though not, I hasten to add, because I have any moral issues with it. I think the view of homosexuality as a "sin" or "perversion" is idiocy, plain and simple, and I actually have a number of good friends who are gay. No; my main quibble with slash, whatever the fandom, is that so many people seem to write it purely for the sake of writing it, and not because there is any of what I would call compelling evidence for such a relationship between a given pair of characters. The fact that Character A and Character B are both hot is, for me, not nearly enough justification for slashing the two of them, but it seems to be so for many other authors, and if that's their thing, well, what the hey--who am I to tell them what they should or shouldn't write? I just stay out of their communities, they (I assume?) stay out of mine, and everyone is happy.
Short for "hetero" or "heterosexual," het fics are the opposite of slash and involve romantic relationships between two characters of opposite gender.
A rather colorful synonym for "disgusting" or "disturbing." An entire academic dissertation could likely be written on why, but the fact of the matter is that there's a lot of sex and violence involved in fanfic, and both are sometimes depicted in quite graphic detail. Many authors give their fics a rating in the manner of a motion picture to indicate that the content may not be suitable for all comers, but this isn't always totally effective--and if you get hold of something that you'd really have been a lot happier not reading, you've just been "squicked out."
An acronym which stands for "alternate universe," this term refers to a device sometimes employed by fanfic authors wherein they are selective about which aspects of their fandom they incorporate into a story. Sometimes people will write about the same characters but transplant them into a completely different setting, or change some key happening in canon (or real life) and end up with a kind of alternate history.
A fic that combines two different fandoms within a single story. Sometimes this is done for purely humorous effect, but not always.
An acronym which stands for "Real Person Fanfic." Usually these are written about musicians (also sometimes called "musicfic" or "rockfic") and actors, and I have a few more issues with these types of stories than most other kinds of fanfic. My own feeling is that the ethics of writing about a real person are shakier than simply imitating what another author has done in a fictional context; it seems like an invasion of their privacy, and particularly since a great many of the RPFs that I have ever seen are slash--and the people about whom they are written are known to have other preferences. I'm not necessarily for banning this kind of fic completely (I've been known to write them on occasion myself, after all) but I do think RPF takes a very fine touch to do well, and unless you're certain that you can handle the subject gracefully, perhaps better not attempted, or at least not in a public setting...
A term of my own invention, to describe stories that straddle the line between "traditional" fanfic and RPF. Basically, the idea is that such a story will contain one or more characters who are inspired by or heavily based on actual living people, but who are not intended to actually BE those people. It's a bit like taking a real person, turning them into an actor, and giving them a role to play--they'll bring something of themselves to the character, both in looks and perhaps a prominent personality trait or two, but they'll also have a fictional name, occupation, etc. and will usually inhabit a universe that the real person has absolutely no connection to, such as a historical or fantasy setting.
I will be the first to admit that it's a fairly subtle differentiation, but I myself still feel far more comfortable with both writing and reading this type of fic than I am with straight RPF. And, from an authorial perspective, it's also a lot more liberating in terms of subject matter. With doppelganger fics, you're not confined to either settings or plot devices that would be realistic for an actor or a rock star, and--if you intend for your fic to contain a romance--it also neatly eliminates the issue of what to do about a famous person's inconvenient spouse, significant other, children, etc.