1. Glossary: Common HASA Terms
Some of these are general fanfic terms, some are specific to Tolkien fanfic or even HA and HASA. For general fanfic terms there is a much more comprehensive Fanfiction Glossary. The same site has a general internet abbreviation glossary here.
AU: Alternate Universe. There is a lot of discussion about the exact definition, but a good guide is that something about the source material, ie book or movie, has been changed. The story can not fit into the original, for example: Boromir didn't die, Frodo kept the ring, Feanor only made one Silmaril. This is distinct from taking the same events and interpreting them differently.
Beta: A section of HASA containing stories that are still being worked on by the authors. It is assumed that an author welcomes comments and suggestions on a story 'In Beta.' (Of course, most authors welcome comments on any story they've written.)
Beverage warning: Don't drink anything while reading this if you don't want your screen sprayed when you laugh explosively.
Bookverse: The story is based on the book version of LotR, or 'book universe'.
Canon: The source material, any book of Tolkien's for bookverse, the movie for movieverse.
Challenges: Ideas for stories that are promoted to stir members to write stories within a specified time limit. They may be related to a holiday, place, character, or just about anything else. Any story idea that gets 5 volunteers who agree to write it becomes a challenge. If you value your free time, run screaming from the Challenge Managers.
Drabble: A story of exactly 100 words with up to 15 words for the title. Some sites also recognize half drabbles and double drabbles.
EoA: Encyclopedia of Arda. Online encyclopedia with a broad range of information. It unfortunately lacks citations, so there is no way to go back to the source material. Great for quick look-ups.
Fanon: Inventions of fans that are so widespread or have been repeated so often that they are mistaken for canon. Some examples are Thranduil as an abusive father, or Legolas and Aragorn as friends prior to the Council of Elrond.
FF.NET or FF.net: Fan Fiction.Net. A huge archive of Fan Fiction from hundreds of books, movies, cartoons, TV serials, etc. Quality varies wildly.
Filk: A rewriting or parody of an existing song, using the same tune but new words relating to a fandom.
Gen: Genre of fanfiction that is not concerned with romance or sex, neither het nor slash.
General: A section of HASA containing stories that are posted by members for members only.
HA: The Henneth Annûn Yahoo Discussion Group, as distinct from...
HASA: The Henneth Annûn Story Archive.
H/C or Hurt/Comfort: Genre of story involving one character getting hurt and another character providing comfort. This abbreviation does not seem to be used much at HASA.
Het: A story involving heterosexual relationships, whether sexual or chastely romantic.
IC: In character
Movieverse: The story is based on 'movie universe' as opposed to 'book universe'.
Mpreg I don't know that you'll see a story like this at HASA, but the term may get mentioned. It means the story contains male pregnancy.
MS or Mary-Sue: An OFC who is too good to be true. She often is a better archer than Legolas, wiser than Galadriel… You get the picture. She frequently becomes the center of the story and causes the canon characters to act OOC - Out Of Character - especially when one or more falls in love with her. Also Marty-Stu for male versions.
MST: A kind of parody where a story is reproduced with commentary inserted, often sarcastic. This comes from Mystery Science Theater 3000, where a human and two robots comment on SF movies, with hilarious consequences. These are not accepted for the HASA public archive.
Nuzgul: The LotR version of plot bunnies. They are plot ideas with sharp fangs that bite and won't let go until their story is written, AKA 'defanged'. The name comes from an unfortunate misspelling of Nazgul, collected by OFUM.
OC: Original character
OFC: Original female character
OFUM: Official Fanfiction University of Middle-earth. Developed by Camilla Sandman in a story of the same name. There is now a website with some hilarious stories and pictures. Miss Cam collects misspelling of character names, and OFUM maintains that any misspelling spawns a 'mini-balrog' with that name; these are put up for adoption. 'Nuzgul' is one, another is HASA's mascot 'Henneth Anun;' we adopted it from OFUM to give it a good home.
Oliphaunts: HASA Challenges whose time limit ran out, but are just too good to let go of.
OMC: Original male character
OOC: Out of character
OSA: Open Scrolls Archive; this archive was set up as a het archive, but will take general stories. It will not take any slash.
Plotbunny: This is a general fanfic term for a story idea that won't go away until you write the story. Around here those are called 'Nuzgul'.
PPC: Protectors of the Plot Continuum. A series of stories about assassins who target Mary-Sues (or Marty-Stus) for distorting canon and characters.
Public archive: (sometimes informally just called 'archive') A section of HASA containing stories that have been through the review process and are posted for the public. This is the only part of HASA accessible to the nonmember.
PWP: Porn Without Plot or Plot, What Plot? Fairly self-evident - sex scenes with nary a plot to be found.
RL: Real life. Usually used to explain why a member can't finish a story faster or read and critique another author's story.
RPS: Real Person Story or Real Person Slash; the slash versions are stories with sexual pairings of the actors who played the characters. Aside from stories where the only real person is either the author of the story or an historical figure, not accepted for the HASA public archive.
Slash: Sexual pairings of canon with canon or canon with original characters, usually refers to same-sex pairings. The pairings are considered non-canon by most people, but it is a popular genre throughout fanfic.
SoA Stories of Arda, an archive that takes stories rated G to R. Does not accept slash.
Squick: Something that the reader may find repulsive or disgusting. Used as a verb, "that squicks me," or a noun, "that's a squick".
SSP: Shameless Self Promotion. Humorous and now standard way to announce on the HA list that an author has posted a new story or updated an existing one. If you are shy, consider it Shamefaced Self Promotion, but do it anyway.
TORn or TORN: TheOneRing.net, the mother of all Tolkien movie sites. It also has quite a bit of book information and discussion, but the main focus is the films.
WIP: Work In Progress, meaning a story that is unfinished. There is a distinction between a story which is finished but is still being polished, and one where the basic story isn't finished yet. In the WIP the author is still writing the basic story, and may be posting it in sections; for example, a story that will ultimately be 10 chapters long may have only 5 chapters written. In the latter the story is done, but the author may be hunting down typos, rephrasing, perhaps reworking sections; this story is said to be in 'beta' or being 'betaed'.
BoLT: Book of Lost Tales I and II. These are the first two volumes of the HoMe set. As Mike Kellner so aptly described them; "Middle-Earth's Dead Sea Scrolls."
HoMe or HoME: History of Middle-earth. A 12 volume set by Christopher Tolkien detailing his father's previously unpublished works, early drafts, blind alleys, and contradictions. Fodder for arguments over 'what Tolkien really meant'. Some of the ones very frequently referred to are
LR: The Lost Road - HoMe 5, contains the etymologies of various words in Sindarin and Quenya.
MR: Morgoth's Ring - HoMe 10 and the repository of Tolkien's thoughts on Elven sex and marriage customs. See LACE.
PoMe: Peoples of Middle-earth - good source of information on the various races, plus clarifications of a few sticky points.
LACE or LaCE: Law and Customs among the Eldar, the section of Morgoth's Ring (HoMe 10) which deals with Elven sex and marriage, among other things.
Letters: The Letters of JRR Tolkien
LotR: The Lord of the Rings containing
FotR, Fellowship of the Ring;
TTT, The Two Towers; and
RotK or RK, Return of the King.
Sil or Silm: The Silmarillion
TH The Hobbit
UT: Unfinished Tales.
Commonly used net abbreviations you may see on HA or HASA
AFAIK: As far as I know.
BTW: By the way.
HTH: Hope that helps.
IIRC: If I recall correctly.
IMHO: In my humble opinion. Variants JMHO - just my humble opinion, IMO - in my opinion, and IMNSHO - in my not so humble opinion.
LOL: Laughing out loud.
OMG: Oh, my god!
OT: Off Topic.
ROTFL: Rolling on the floor laughing. Also ROTFLMAO which is Rolling on the floor laughing my ass off.
TBC:To Be Continued.
TIA: Thanks in Advance.
TTFN: Tata for now.
YMMV: Your mileage may vary, translated as 'you may feel differently about this'.