When I was new to the writing community, these terms mystified me. They were EVERYWHERE, yet with no explanation. So, I hope this can make things less confusing.
ABA – American Booksellers Association
ARC – advanced reading copy (This is generally sent out to select readers before publication in exchange for reviews.)
AU – alternate universe (Mostly a fanfiction term)
BCC – back cover copy (This would include the blurb and short synopsis. Basically it's your selling pitch that would be printed on the back cover to interest potential readers.)
Beta Reader – a person who reads a manuscript and gives feedback on issues before publication
Character Chat – Used by writers (with other writers) to flesh out characters. Partners will roleplay as their characters.
Charrie – short for character
Elevator Pitch – a short description of the story that can be said in thirty seconds (roughly the time of an elevator ride)
FMC – female main character
K – thousand
MC – main character
MMC – male main character
MS – manuscript
NaNoWriMo – National Novel Writing Month; Month in which writers can participate in a contest to complete 50,000 words in thirty days. Held largely in the U.S.A. and always in the month of November.
OTP – one true pairing (fandom term)
OP – out of print
POV – point of view
Query Letter – letter to an agent or editor to pitch your work
SASE – self-addressed stamped envelope
Ship – couple (Fandom term)
WIP – work in progress
Word War – A period of time set by the players in which you attempt to write more words than your opponents.
Zero Draft – A ‘draft’ comprised of various scenes of the story. Many prefer the zero draft as an alternative to beginning with the first draft.