AC - "Armor Class". A measure of how strong your character's armor is. Used to calculate whether or not an attack hits your character.

Class - This describes your character's occupation. For example, they could fight for a living (fighter), heal for a living (cleric), or steal for a living (rogue). There are usually a large number of classes to choose from, depending on the game.

CR - "Challenge Rating". A measure of how difficult a monster or encounter is. Judged by a party-of-four standard; in D&D, an encounter with a CR of 7 would be a good challenge for a party of four 7th-level characters.

d - An abbreviation for "die". Usually preceded and followed by numbers indicating how many rolls to make of which type of die. For example, 1d8 means 1 roll of an 8-sided die. 2d4 means 2 rolls of a 4-sided die, and so forth.

D&D - "Dungeons & Dragons"

DM - "Dungeon Master"; see GM.

Encounter - A single meeting between the player characters and a challenge. The challenge could be a monster, a trap, or a puzzle of some sort.

HP - "Hit Points" or "Health Points". A measure of how much physical damage your character can take before they are rendered unconscious or killed.

Gamer - Someone who spends a substantial amount of time playing computer or sit-down role-playing games. A member of the gaming subculture. Very generally, a creative, intelligent individual who enjoys the science fiction and fantasy genres. Though most gamers are male, the female gamer population is fast-growing.

GM - "Game Master". The person who hosts a game, makes rules decisions, presents challenges for the characters, and controls NPCs. The GM is the final authority on all decisions within their game. Also commonly known as a DM (Dungeon Master) or ST (Storyteller).

LARP - "Live Action Role Playing Game". An RPG that is physically acted out, either through simple movement and props, or through combat with the use of padded weapons (a "boffer LARP"). All have rules about touching other
players, and actions and props that are appropriate.

Min/Maxing - "Minimizing/Maximizing". In character creation, the act of minimizing certain of your character's abilities in order to maximize others. A typical example is the fighter who spends few or no points on their intelligence
score in order to maximize the points they can spend on their strength score.

MMORPG - "Massively Multiplayer Online Role Playing Game"; a persistent computer game played over the Internet where hundreds or thousands of players are logged in at any given time. Some examples are World of Warcraft and Everquest.

Munchkin - A player who values action over role-play. Prone to hack-and-slash, min/maxing, and powergaming.

Newbie - Someone who is new to role-playing games in general, or new to a specific role-playing game. Sometimes used as a derogatory term for someone who doesn't know what they are doing. Also "newb" or (regrettably) "n00b" or "n3wb".

NPC - "Non-Player Character". A character in a role-playing game who is controlled by the game server or the GM rather than by a player.

PC - "Player Character". A character in a game who is controlled by a player.

Powergamer - A gamer who puts power above all other considerations when playing their chosen game. They will always use the best weapon, the best armor, and the best skills to maximize their character's power, even if those things do not fit their character's concept. Sometimes accused of "playing to win", rather than playing to enjoy the game or to develop a character.

Race - Your character’s species. For example, your character might be a human, elf, dwarf, halfling, etc.

RPG - "Role-Playing Game". A game in which the player takes on the role of someone else -- typically a fantastic creature or person with supernatural skills and powers.

Rules Lawyer - A gamer who frequently argues about rules calls. Also known as the thorn in the GM's side.

Stats - "Statistics". Numbers which represent your character's basic abilities, typically strength (STR), intelligence (INT), wisdom (WIS), dexterity (DEX), constitution (CON), and charisma (CHA). Different game systems have different names for stats, and some systems have greater or fewer stat categories. Also used to indicate the attributes of items or NPCs.

Twink - Someone who knows the game very well, and can twist the rules or exploit existing loopholes for their character's gain. Often say things like, "Well, the rules don't say I *can't* do this..." Also known as the thorn in the GM's other side.

WotC - "Wizards of the Coast", the company that produces Dungeons and Dragons.