4/5A = longer mini battery cells, generally greater mAh capacity
ABS = Acrylonitrile-Butadiene-Styrene. A fairly tough plastic material.
ACU = Army Combat Uniform. All-terrain (phft!) Army version of MARPAT.
AE = Airsoft Elite. American upgraded version of ICS. Also maker of high-quality BBs.
AEG = Automatic Electric Gun. What you should be using if it's your first airsoft model.
ALICE = All-purpose Lightweight Individual Carrying Equipment. Old Vietnam-era stuff, still pretty useful.
AUC = Army Universal Camouflage. Another name for UCP.
BDU = Battle Dress Uniform. There's an oxymoron if I ever heard one.
BHI = BlackHawk Industries. Makers of a lot of wanna-be gear, with groovy elite-sounding marketing terms like, "STRIKE" and "Hellstorm." Some overpriced, some fairly inexpensive, a lot but not all completely shit products.
BOHICA = Bend Over, Here It Comes Again! What you should do if you get FUBAR'ed twice.
bullpup = A weapon whose action takes place behind the trigger group. Translated, the magazine is located behind the trigger. The Steyr AUG, GIAT FA-MAS and FN P90 are examples of bullpup assault rifles and submachine guns.
CA = Classic Army. Hong Kong-based manufactuer of AEGs, mostly MP5s and M16 variants, but expanding with every new release. Far improved quality control in most recent batches of manufacture.
clip = What a magazine is not.
COMINT = COMmunications INTelligence
CQB = Close Quarters Battle
CQC = Close Quarters Combat. Same thing as CQB.
deagle = What a Desert Eagle is not.
deuce gear = Second line gear; carrying all your ammo, grenades and a few other field essentials.
EBB = Electric Blowback. Beer can plinking pistol.
ELINT = ELectronic INTelligence
EOD = Explosive Ordnance Disposal. What you don't need in airsoft.
frag = Short for fragmentation grenade. What a 'kill' is not.
FN = Fabrique Nationale. Belgium weapon manufacturer.
FPS = Feet Per Second
FUBAR = Fucked Up Beyond All Repair (doesn't get worse than this)
G&P = Makers of double-stacked standard magazines (mid-caps). Highly recommended.
GBB = Gas Blowback. The slide recoils like the real thing.
GLOCK = Reliable pistols made by GLOCK in Austria. And yes, all the letters are capitalized like that.
GP = Gold Peak. Some of the best cells for airsoft battery packs.
HFC134a = Gas meant for stock gas models, and especially Japanese versions like KSC and Western Arms.
HFC22 = More powerful gas, for NBB, upgraded and non-Japanese gas models.
HG = High Grade. Better quality than previous models. In the case of Tokyo Marui MP5s, improvements include metal parts and heavy duty internals.
hi-cap magazine = High Capacity magazine. BBs dumped into a resevoir, then the magazine is wound up to provide tension on a spring to feed the BBs. Ammo capacity generally run 200 to 600 rounds.
HK = Heckler & Koch. German manufacturer of ultra-reliable pistol, submachine gun and assault rifle.
HUMINT = HUMan INTelligence
HW = Heavy Weight. A material generally heavier and stronger than ABS plastic.
ICS = I Chih Shivan. Taiwanese manufacturer of AEGs, every MP5 model and various M16s. Less maintanence and better quality control (in newest versions) than Classic Army, but also less prevalent.
IED = Improved Explosive Device. MacGyver bomb.
IMINT = IMagery INTelligence
KIA = Killed In Action
KISS = Keep It Simple, Stupid. What all operational plans should be.
LBV = Load Bearing Vest. Generally a non-modular, standalone vest. Some of the nicer ones are customizable either by the manufacturer (CSM) or have optional accessories available (SOE/BDS). Was standard issue after ALICE gear but before the introduction of MOLLE.
mAh = milliamp hour; battery power storage
MARPAT = MARine PATtern (camouflage). That digital stuff that comes in woodland and desert patterns.
MASINT = Measurement And Signature INTelligence
MIA = Missing In Action
Mil-Spec. = Military Specifications
MOLLE = MOdular Lightweight Load-carrying Equipment. Pronounced, "Molly". Modern modular gear, lots of options.
MOUT = Military Operations on Urbanized Terrain
nade = What a fragmentation grenade is not.
NBB = Non-blowback. The slide is fixed, generally more powerful than GBB.
NEASG = NorthEastern AirSoft Group. The most well-organized airsoft community in the U.S.
NiCad/NiCd = Nickel Cadmium
NiMH = Nickel Metal Hydride
OD = Olive Drab (camouflage)
PALS = Pocket Attachment Ladder System. The webbing on the back of MOLLE gear.
PDW = Personal Defense Weapon. Generally a small automatic weapon you can hide under a long coat.
PERSEC = PERsonal SECurity. What you're not engaging in by posting information and photos of yourself on the internet.
recon = reconnaissance
ROE = Rules Of Engagement. What you're allowed to do when you come into contact with the enemy.
ROF = Rate Of Fire. How many rounds you shoot per time interval, generally per minute.
RPM = Rounds Per Minute. Another form of rate of fire.
RUMINT = RUMor INTelligence
SCW = Shibuya Custom Works. Smaller sub-section of Western Arms that puts out higher quality models.
SDS = Specialty Defense Systems. Makers of MOLLE gear supplied to the US military. Most of it quite good, with the FLC being one of the better modular vests I've ever used.
SIGINT = SIGnals INTelligence
SMG = submachine gun
SNAFU = Situation Normal, All Fucked Up (proceed to TARFU)
SOE = Special Operations Equipment, now BDS Tactical. Maker of the finest LBVs.
springer = Air-cocking airsoft model. Can range from reliable (Tokyo Marui) to worthless (HFC).
standard magazine = BBs rammed down the magazine and feed up via internal spring. No winding required. Ammo capacity generally runs 50 to 150 rounds.
sub-C = standard large battery size cells
SWAT = Special Weapons And Tactics police teams. All too often they do not train enough, and become SQUAT teams.
TARFU = Things Are Really Fucked Up (proceed to FUBAR)
TECHINT = TECHnical INTelligence
TM = Tokyo Marui. Japanese airsoft model manufacturer. The best, low maintanence AEGs available, however made of plastic and low boiling point metal.
TT = Tactical Tailor. Makers of some great modular gear, very affordable.
UCP = Universal Camouflage Pattern. The camouflage pattern ACU is made of.
USA = United States of America; also: United States Army
USAF = United States Air Force (AKA: Air Farce)
USMC = United States Marine Corps (also: Uncle Sam's Misguided Children)
USN = United States Navy
v = volt; battery power output. 8.4v is recommended for stock (non-upgraded) AEG models.
WA = Western Arms. Really expensive gas pistols/display models
Whiskey Tango Foxtrot = See: WTF
WIA = Wounded In Action
WTF = What The Fuck? (also: Whiskey Tango Foxtrot)