Below is a list of abbreviations/terms that you might see and their definitions. Not including stuff you should know like Lol or PvP.
BP - Back Pack
CM - Crystal Market
Cor - Corrode
CT - Crystal Thought
Depo - Deposit
DP - Data Processor
EoC - End of Content
ES - Entity Seeker
Exp/xp – Experience
FC/FCz - Flux Crystal
FE - Full Engineered
FF - Full Forged (used in FS but might slip over to SS2 on occasion)
FI - Find Item
FS - Fallen Sword
GS - Guild/Faction Store (it's guild in FS but because FS is already taken by Fallen Sword, we can't use that to talk about the store. Thus, we use GS for simplicity)
HL - High Level
Hunting - Going out and killing entities for experience and/or credits
Ints – Intensifier
IR - Internal Reserves
KR - Kinetic Reserves
LL - Low Level
MF - Mission Finder
MS - Mental Shield
Msg – Message
NE - No Engineered)
NF - No Forged (used in FS but might slip over to SS2 on occasion)
Res – Researcher
SS2 - Sigmastorm 2
SS2helper - SS2 Helper (Greasemonkey addon to make life a lot easier)
ST - Secure Trade
TH - Trade Hub
Tra/Trav - Traverse
More coming as I think of them and remember to add them.