OP can mean Original Post, Original Poster, or Over Powered, depending on where/how it's used.

Also, some others I've seen floating around these forums:

MSE = Mask Energy Signature
SNB = Sub-Nucleonic Beam
VM = Viral Matrix

(Why, yes, I play Science; why do you ask? :p)

FI = Full Impulse (when in reference to engines)
EPtS = Emergency Power to Shields

I can't think of any others at the moment, although I'm sure there's plenty more lol.

just browsed the new list quickly, but it all seems well layed out, useful and correct as far as i could tell. This is a very good resource for new players imo

Others you may come across from experienced players.

BoE = Bind On Equip. Admittedly only a few items in Star Trek so far seems to be anything but.
BoP = Bind On Pickup

just in in case there are really new players who don't know what that means, bind on equip is an item that you cannot trade after you have equipped it to yourself. You should check these carefully if you want to trade them because once you have equipped them you can no longer trade to other players or vendors. Your replicator only gives you a small amount of credits for the item.

Bind on pickup is similar but you cannot trade once you have picked the item up

ESD = Earth Star Dock
SB39 = Star Base 39 (Sierra)
K-7 = Deep Space K-7
DS9 = Deep Space 9 (station & the show)
Mem-A = Memory Alpha
Kling = Klingon
Rom = Romulan
Fed = Federation
Adm or Adml = Admiral
Lt = Liuetenant
LtCm or LCmd or LC = Lt. Commander
Cmd = Commander
Cpt = Capitan

Thats all I can think of for now.

peter

I guess you can also have
EPtW = Emergency Power to Weapons
EPtA = "" "" "" Aux.
EPtE = ditto Engines

peter

Most of them aren't acronyms, they're contractions.

Thank you, I have updated the OP to compensate for this error.

I just want to point out that:

"Naval Construction Contract" is actually "fanon" and "United Space Ship", while never mentioned on screen, was mentioned in an old tech manual old Reddenberry himself provided input for. It makes more sense for it to be "United Star Ship", these days tho.