BoE - Binds On Equip
OP - Overpowered
FD - Flawless Dawnbreaker, the "PVE morph" of the Fighter's Guild ultimate, Dawnbreaker. If it was in Cyrodiil, they could also have meant Fort Dragonclaw, people usually abbreviate keep names there
LFG - Looking For Group
HoF - Halls of Fabrication (a 12-man trial)
DDA - Do you mean DSA? That's Dragonstar Arena, basically a 4-man trial in Craglorn. Dunno what DDA is
DBOS - Dawnbreaker of Smiting - the "PVP morph" of Dawnbreaker
PUG - Pickup group, or people that you're grouped with randomly
DD - Damage dealer, also commonly known as DPS, or Damage-Per-Second
vAA - Veteran Aetherian Archive (the harder, or veteran, version of a 12-man trial)
MSA - Maelstrom Arena. I had to look this one up- typically I use and see the abbreviation vMA, or veteran Maelstrom Arena
COH - Crypt of Hearts, a dungeon
WB - World Boss
BiS - Best in Slot
FTP - Free to play
SPC - Spellpower Cure, a popular gear set for healers
Squatting action over your corpse = is a tea bag or changing frame of mine "good game"/"GG"
(I know its not a abbreviation, but may if needed it cleared up aswell )