Terminology

Role playing is full of a lot of jargon. To make this worse a lot of games have their own sub-set of acceptable jargon, meanings which differ in various ways from generally accepted versions. This means that definitions of terminology can vary widely between games. Here is a list of jargon and terminology that we use here in this game.

A-B

Alternate Reality: An alternate version of an existing reality, similar to an Alternate Universe but occasionally (but not always) refers to changes on a broader scale.
Alternate Timeline: An alternate (usually artificially made) timeline, similar to an Alternate Reality or Universe but in this case often refers to one created through interference by a particular person, either on purpose or accidentally.
Alternate Universe: An alternate version of an existing universe. (see Multiverse)
AU: Alternate Universe
Bio: Sometimes refers to a character bio but can also refer to taking a break for biological reasons (i.e. using the bathroom).
Bunnying: See Power Gaming

C

Canon: Anything written in original source material, sometimes restricted to a single (original) author of source material. Please see the Merriam-Webster dictionary entry, specifically definition 3, or the Oxford English dictionary entry, specifically definition 2.
Character Bio: Similar to a character sheet, but focuses less on stats and more on personality, background, and abilities. Used mostly in FFRP games in place of a character sheet.
Character Sheet: A sheet (or document file) that contains all the stats of a particular character with emphasis on scores in various abilities and skills along with an inventory of equipment. Character sheets focus on stats and abilities used in dice rolling games to determine outcomes. Often character sheets are light on details such as personality, character history, and other information one might find in a character bio. Mostly used for dice-based / table-top games.
Combat Rounds: In many games combat is played differently than non-combat play. Being in combat rounds specifies that a game is being played within that context. Combat rounds tend to be more organized and use initiative to decide the order which actions happen, rounds to determine how much time is passing, and often wait until all active players have posted before moving from one round to the next. While this can significantly impact the speed of play, making things slower, it is also more organized and helps to ensure all players (no matter how fast they can type) get equal time playing characters and are given the opportunity to enjoy the game. Often combat rounds, even in FFRP games, uses some form of dice to determine the outcome of certain aspects of the game play.

E-I

ERP: Erotic Role Play
FFRP: Free Form Role Play / A form of role playing that focuses more on writing and less on dice rolls. These games do not follow a system such as d20, Rifts, or Vampire the Masquerade but instead follow plot lines using free interaction between characters of various types.
Gary Stu: A male version of a Mary Sue.
Godmoding: The practice of playing a character to be invincible or otherwise untouchable, often times going well outside of the bounds of reason even in a made-up world.
Head Canon: An erroneous term referring to ones own additions to a pre-existing storyline, character, or particular story element. This is an erroneous term as canon is defined to be something contained in original source material. This term refers mostly to a complete and sometimes elaborate sets of alterations and additions to canon which encompass someones personal interpretations and vision for where they feel a story could have or should have gone. Such sets of alterations would fall into the category of a Alternate Reality or Alternate Universe.
IC: In Character
Initiative: In a role playing context this refers to the order in which actions are taken by players. It is usually understood that while a particular scene may be organized by some form of initiative (relating to speed) saying who gets to act and when, the actions happen roughly simultaneously. This term comes from table-top role playing.

M

Marty Stu: A male version of a Mary Sue.
Mary Sue: A particular kind of character, that embodies absurd wish fulfillment for the player. Usually an indicator of an inexperienced or immature player.
Metagaming: When a character is played with and reacts to / uses knowledge the player has for which the character has no way to know. Another way to put this is when a player uses what they know OOC to influence their character(s) even when the character(s) have no way to know said information.
Mun: See Mundane
Mundane: A term for a player often used in Journal based games (such as games played over mediums like Live Journal, Greatest Journal, Insane Journal, etc..). Not often used in live chat or forum role plays.
Multiverse: A collection of multiple universes bundled together by a common threat, also refers to the idea of multiple universes where any potential outcome creates its own universe where things are different from the current one. This generally carries that idea that for any particular set of conditions there is an alternate universe where that set of conditions exists.
Munchkin: A character that is entirely too powerful for the setting, similar to power gaming but in this case, the characters aggressively seek out situations to use their power in, even if those powers would never be reasonably called for.
Muse: Source of inspiration and creativity. Sometimes referring to where a writer looks to for inspiration (i.e. a person), though at times this is also erroneously used to refer to a persons character. Writers block will often be described as ones muse being burned out, missing, dead, or otherwise unavailable.

N-O

Non-Con: Non-consenting role play, usually referring to an ERP scene where one player chooses to play a character being taken advantage of, raped, or otherwise unable (or unwilling) to give consent to what is going on.
NPC: Non-Player Character, analogous to an extra in a movie or TV show. Someone who is there to facilitate the story and nothing more.
One Liner: A response to a (usually long) post which is entirely too short, usually one single line.
OOC: Out of Character

P

PbEm: Play by Email / Playing a role playing game via email being sent back and forth.
PbP: Play by Post / Playing a role playing game via posts on a forum.
PC: Player Character
Post: A single block of text encompassing a characters action, dialog, thoughts, or any combination there of.
Power Gaming: Playing an exceedingly powerful or overpowered character and/or using that characters abilities excessively in such a way that suppresses or discourages the role playing of others.
PvP: Player vs. Player when two players pit their PC's against each other.

R-S

Retcon: Retroactive Continuity / To retroactively adjust previously stated events in such a way that they now have an entirely new context and meaning, also refers to adding previously unknown elements into a story line. In either case, this is done to facilitate a new story line or a new understanding of a character or plot point in order to open up new avenues of creative writing.
Round: A segment of time within an organized turn-based role playing scene. Usually encompasses some standardized segment of time (15 seconds, 1 minute, etc..) used to measure our spell effects, how much time a character has to complete an action, and what kind of actions can be done / how long they last compared to the actions of others. This term comes from table-top role playing.
Scene: A particular role playing session, in character. Much like a scene in a play this can be a small chunk of a larger role play or just a single session played independently.
Sheeted Game: A game that requires characters to have character sheets with explanations on stats, skills, inventory, and other such things. Such information is often required to facilitate dice rolls or other forms of introducing random chance into a game when deciding outcomes.