This guide (A - M) is for those who are brand-new to either MMO's or CoX (City of Heroes / City of Villains). If you hear a strange anocrym or phrase or word, you can look here for it! It will also increase your vocabulary (not really), make you more fun (not likely), and even help you impress your friends (yeah, right)! So, let's get started! And, because I have
WAY too much time on my hands, it's alphabetized!
All swears are replaced with a word with the same meaning in parenthesis and colored red "(word)".
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A[/list]
AB:
Noun, CoX specific. Stands for "Adrenaline Boost", a power (buff) in the Empathy set.
AFK:
Adjective. Stands for "Away From Keyboard". Means the player is away or busy and won't respond.
Aggro:
Verb/Noun. Short for "Aggravate" or "Aggravation". How "angry" an enemy is toward a specific character and the likeliness it will attack only that character. To "Aggravate" means to draw enemies' attacks.
AM:
Noun, CoX specific. Stands for "Accelerate Metabolism". A Radiation Emission power in CoX.
AoE:
Noun. Stands for "Area of Effect". Refers to any power that affects multiple foes in an area.
AP:
Noun, CoX specific. Stands for "Atlas Park". A starter zone in CoH.
Atlas Park Info
AT:
Noun, CoX specific. Stands for "Archetype". The basic "classes" of heroes and villains. (Blaster, Scrapper, Corruptor, Stalker, etc.)
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B[/list]
Baddies:
Noun. A group of bad characters, "bad guys", villains, etc.
BB:
Noun, CoX specific. Stands for "Bloody Bay", a PvP zone in CoX.
Bloody Bay Info
BF:
Noun. Stands for "BoyFriend". You don't need a definition of
that...
BFF:
Noun. Not typically (almost never) used in an MMO. Stands for "Best Friend Forever". (Also, "BF" for Best Friend)
Bio: 1.
Verb. Usually follows "BRB" (as in: Brb, bio), means the player is going to the bathroom. 2.
Noun. A character's biography. Info about a character.
BRB:
Verb. Stands for "Be Right Back". Means the player is temporarily "AFK" (
see "AFK" above) but will return shortly.
Buff:
Noun. A power (or anything in-game) that grants a bonus (improvement) to a character in any way.
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C[/list]
Character:
Noun. Any person (sometimes thing) in a game. Usually someone (something) that has at least some impact on the game.
Cimerora:
Noun, CoX specific. A zone in CoX. You must be a member of the Midnight Squad to enter.
CM:
Noun, CoX specific. Stands for "Clear Mind", a power (buff) in the Empathy set.
CoS:
Noun, CoX specific. Stands for "Carnival of Shadows", a villain group of CoX.
Carnival of Shadows Info
CoT:
Noun, CoX specific. Stands for "Circle of Thorns", a villain group in CoX.
Circle of Thorns Info
CoX:
Noun. Stands for "City of Heroes / City of Villains". (CoH refers to City of Heroes / CoV refers to City of Villains).
Craft(ing):
Verb. To make something using materials in-game. Sometimes used as a noun referring to something that has been crafted (a "craft").
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D[/list]
DBK:
Verb. Stands for "Death By Keyboard". When, due to some error such as: typing but forgetting to press enter, pressing "f" or "r" by accident, etc., a character dies.
DC:
Verb. Stands for "DisConnected". Means the player lost connection.
DoT:
Noun. Stands for "Damage Over Time". Any power or thing that causes damage over an extended period of time. (i.e. causes four damage every two seconds for ten seconds)
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E[/list]
Effin:
Noun. Spelled multiple ways. Short for a bad word that starts with an F. You know what one...
'em:
Noun. Short for "Them".
End:
Noun, CoX specific. Short for "Endurance". Used in CoX.
ET:
Noun, CoX specific. Stands for "Energy Transfer", a power in CoX. (Can also refer to Extraterrestrial...)
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F[/list]
FF:
Noun, CoX specific. Stands for "Founders Falls". A zone in CoX.
Fort: 1.
Noun, CoX specific. Short for "Fortitude". An Empathy power in CoX (buff). 2.
Noun, CoX specific. Short for Fortunata, a type of enemy in the Arachnos villain group.
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G[/list]
GF:
Noun. Stands for "GirlFriend".
GG:
Noun. Stands for "Good grief! / Good God!".
Gimme:
Verb. Short for "Give me".
GJ:
Noun. Stands for "Good Job!". Usually said when a mission or hard enemy has been defeated.
GM: 1.
Noun. Stands for "Game Master", a character controlled by a developer. 2.
Noun, CoX specific. Stands for "Giant Monster". The highest (hardest) level / tier of enemies in CoX.
Giant Monster Guide
Group:
Noun. A group, team of players or enemies. Can refer to a team, super group, RP group, mob, or anything like that.
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H[/list]
Herd:
Verb. When a player (usually a "Tank"), gathers a scattered group of enemies (sometimes all over the map) to a specific point.
HO:
Noun, CoX specific. Stands for "Hamidon Origin [enhancements]", a type of enhancement in CoX.
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I[/list]
Inc:
Verb. Short for "Incoming!". Means a group of enemies is on its way towards the players.
Insp:
Noun, CoX specific. Short for "Inspiration(s)", used in CoX.
IO:
Noun, CoX specific. Stands for "Invention Origin [enhancments]", a type of enhancement in CoX.
ITF:
Noun, CoX specific. A task force run in Cimerora. For levels 35+. (See "TF [Task Force]" in the N-Z guide)
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J[/list]
JK:
Verb. Stands for "Just Kidding!". Used when someone isn't serious about what they just said.
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K[/list]
K:
Adjective. Short for "Okay". KK and OK are also used.
Kheld:
Noun, CoX specific. Short for "Kheldian". A race in CoH. Either the AT PeaceBringer or Warshade.
Kin:
Noun, CoX specific. Short for "Kinetics". A power set in CoX used mainly by Controllers or Corruptors.
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L[/list]
LCtMS :
Adjective. Stands for "Lost Connection to MapServer". Similar to "DC" (
above).
LD:
Adjective. Stands for "Link Dead".
Lmao:
Verb. Stands for "Laughing My
(butt) Off!" Used when something is very funny.
Lol:
Verb. Stands for "Laugh out Loud". Used when something is funny. Often capitalized to show extra humor (LOL).
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M[/list]
MA: 1.
Noun, CoX specific. Stands for "Martial Arts", a power set in CoX. 2.
Noun, CoX specific. Stands for "Mission Architect", a new feature in CoX.
Mission Architect Info
Mez:
Noun. Short for "Mesmerize". Basically, anything that causes an enemy to stop attacking. (Sleep, hold, stun, etc.)
MM:
Noun, CoX specific. Stands for "Mastermind", an AT in CoV.
Mob: 1.
Noun. An enemy (singular). 2.
Noun. Used to refer to group of enemies (
incorrectly).
That's it for the first guide! If you see any errors or think of words you think should be added, post 'em! Second guide (N-Z) will be out shortly. Thanks!

Note:
Thanks to everyone who continue to throw out more suggestions! Contributors so far include:
Morbid_Star
Over_Knight
Tripp_Hazard
The Reactor
Aggelakis