Below are the most commonly used acronyms in game.

Acronyms for custom gears, quests, and such.

BCA = bloody_card_album

C = Credit / 100 Point Coin

CoC = clip_of_consciousness

EP = Event Point

GB = goblin_bow

GDS = Great Demon's Shroud

GDP = Great Demon's Pauldrons

GR = Goblin Revoler/Ghostring

GOB = great_old_boots

GOC = great_old_cloak

GOH = great_old_hauberk

HoA = hall_of_abyss

HSK = hardened_steel_katar

IBPC = Itty Bitty Poring City

MCA = mystical_card_album

MMM = Murderous Mystery Mines

LBW = Large Blue (Angel)Wing

LRW = Large Red (Angel)Wing

LWW = Large White (Angel)Wing

OCC = orc_champion_card

OCH = orc_champion_helm

OKC = orc_knight_card

OKP = orc_knight_plate

RDC = Royal Dispatch Center

SBK = Sewer Bug King

SBQ = Sewer Bug Queen

SI = Staff Infection (GM Guild)

VP = Vote Point

VVVSHX= Very Very Very Strong Hardened Sword/Spear/Mace/Dagger

WoWW = Wise Old Woman's Wand

On any RO you go to, these acronyms may be used.

AA = ArchAngeling

AK = Abysmal Knight

BB = Bloody Branch/Bowling Bash(?)

BG = Battle Grounds / Bubble Gum

CW = Cursed Water

DB = Dead Branch

DI = Dark Illusion

DL = Dark Lord

EE = Enriched Elunium

ED = Evil Druid

EO = Enriched Oridecon

EDP = Enchant Deadly Poison/Poison Bottles

ESL = Evil Snake Lord

FBH = Fallen Bishop Hibram

GEC = General Egnigem Cenia

GTB = Golden Thief Bug

HOTB = Horn of the Buffalo

HWC = High Wizard Card/Hill Wind Card

KvM = Kreiger Von Midgard (Type of BG)

LKH = Lord Kaho's Horn

OBB = Old Blue Box

OCA = Old Card Album

OL = Orc Lord

OP = Over Powered

OPB = Old Purple Box

LoD = Lord of Death

PD = Perfect Dodge

PoS = Piece of Shield

PvE = Player Versus Environment

PvM = Player Verus Monster

PvP = Player Versus Player

RoFL = Ring of Flame Lord

RoR = Ring of Resonance

SK = Stormy Knight

SS = Sealed Shrine

SW = Skeleton Worker

TG = Turtle General

ToZ = Token of Ziegfried

THQ = Treasure Hunting Quest

VA = Valkyrja's Armor

VR = Valkyrie Randgris

WoE = War of Emperium

YG = Yellow Gemstone

Certain skills people use acronyms when talking about and the the most common ones are:

AD = Acid Demonstration

BB = Bowling Bash

BS = Beast Strafing

CT = Cart Termination

DS = Double Strafing

HD = Heaven's Drive

HL = Holy Light

FCP = Full Chemical Protection

FJ = Frost Joker

FO = Finger Offensive

FSK = Flying Side Kick

FS = Final Strike

JT = Jupitel Thunder

KE = Kyrie Eleison

LP = Land Protector

LoV = Lord of Vermillion

MA = Meteor Assault

MB = Magnum Break/Mind Breaker

ME = Magnus Exorcismus

PDFM = Please Don't Forget Me

RS = Rapid Shower

SG = Storm Gust

SB = Sonic Blow

SW = Safety Wall

WoF = Wall of Fog

A/B = Auto Buy

A/S = Auto Sell

B = Buying

C/O = Current Offer

OP = Over Priced

PC = Price Check

S = Selling

T = Trading