AAA= anti-aircraft artillery
AC= aircraft, usually helicopters -
        "Choppers"= usually UH-1 "Iroquois" B, C, D, or H model  "Huey" (Bell) helicopters in the Army inventory, Air Force had F models and twin-engine M models, and Marines had some other designations (maybe J models?)
        "Slicks"= earliest slicks were B model Hueys, that after about 1967 were replaced with D or H model Hueys configured as troop lift ships with only two M60, 7.62mm, machine guns mounted one on each side
        "Guns"= normally UH-1C model Hueys configured heavily armored with weapons including 2.75" rocket pods on each side, 7.62mm mini-guns (very rapid fire rate), M49 grenade launcher (mounted under the nose), and anything else the crew could get strapped on the AC and still get off the ground, including the occasional TOW missile. Guns also included the AH-1 Cobra (also referred to as a "Snake") gunship built specifically for armored attack
        "Loach"= initially the OH-6A (Hughes) "Cayuse" was used as a "Light Observation Helicopter" (thus the term LOACH), generally single pilot AC employed as Aerial Scouts to observe the battlefield, direct gunship air coverage and act as an enemy fire 'magnet.'  Later during the Vietnam war the OH-6A was replaced by a more powerful, but less maneuverable (and less crash worthy) , OH-58 (Bell) "JetRanger" AC, but Scouts were always generally referred to as "Loach."
AC= aircraft commander, the "command" authority in an aircraft, generally over any other authority regardless of rank, and generally the pilot with the most time in-country, and the most experience, combat flight hours and missions
AHC= assault helicopter company
AK-47= enemy rifle, standard Warsaw Pact weapon, about .30 caliber size
AO= area of operations, terrain
Arc Light Operations= code name for the devastating aerial raids of B-52 Stratofortresses against enemy positions in Southeast Asia, the first B-52 Arc Light raid took place on June 18, 1965, on a suspected Vietcong base north of Saigon. In November 1965, B-52s directly supported American ground forces for the first time, and were used regularly for that purpose thereafter. B-52 bomb strike often used hundreds of 500lb to 2000lb bombs, so that it actually felt like an earthquake if you were close enough and at the least it sounded like "rolling thunder."
ARVN= Army of the Republic of Vietnam soldiers
ASAP= (pronounced "A-sap") as soon as possible; a request for extreme urgency in a military assignment or operation
Ash & Trash= ASH stands for assault support helicopter (resupply, cargo lift, etc.) & trash means administrative type flying of passengers, VIPs, AC parts, etc., the term applied to any type of non-combat type aviation mission
ASHC= assault support helicopter company, usually CH47 "Chinook" helicopters
A Teams= 12-man Green Beret, Special Forces units

Bag Drag= the last day in-country, the day you left for home was considered the day you drag your duffel bag of junk and memorabilia to the plane
Base Camp= a semi-permanent field headquarters and center for a given unit usually within that unit's tactical area of responsibility. A unit may operate in or away from its base camp. Base camps usually contain all or part of a given unit's support elements.
BDA= bomb damage assessment
Beehive Round= a direct-fire artillery round (usually 105mm howitzer) which incorporated steel darts called 'fleshettes', used as a primary base defense munition against ground attack
Berm= a defensive wall of earth around a military encampment, or gun position, etc.
BIC (biet)= Vietnamese term for "understand" (usually pronounced 'bick' by GIs)
Bird= any aircraft, usually a helicopter
Bird Dog= O-1 Army fixed-wing aircraft used for arial observation
Bladder= a heavy-duty, rubberized collapsible petroleum drum ranging from 2,000 to 50,000 gallons
Body Bag= the plastic bags used for retrieving bodies on the battlefield
BOHICA= short for "Bend Over, Here It Comes Again!" usually describing another undesirable assignment
BooKoo (beaucoup)= Vietnamese/French term for "many," or "lots of"
Boondocks, Boonies, Bush= expressions for the jungle, or any remote area away from a base camp or city; sometimes used to refer to any area in Vietnam
Bouncing Betty= explosive mine that propels up from the ground about four feet into the air and then detonates for more lethal shrapnel effect
Break Squelch= to send a "click-hiss" signal on a radio by depressing the push-to-talk button without speaking, used by LLRPs and others when actually talking on the microphone might reveal their position
Bring Smoke= to direct intense ground fire, artillery fire, air force close-air fire or Spooky "rain of fire" on an enemy position
Bunker= a protective shelter, generally underground and made of concrete (if you were lucky), otherwise it was made of timbers and earth and often portals for firing out toward the enemy

C-4= a very stable plastic explosive carried by infantry soldiers
CA= combat assault (troop insertion or extraction), fully coordinated airmobile operation
CAB= combat aviation battalion, next higher command over a company
Caca Dau= (pronounced "cock ie dow" by GIs) Vietnamese phrase for "I'll kill you."
CAG= combat aviation group, next higher command over a battalion
CAV= nickname for air cavalry, also referred to armored cavalry using M113 APCs, and other light armored vehicles
CCN, CCC, CCS= Command and Control, North (Central or South), the special ops units that ran the clandestine and covert operations in South East Asia
CE= crew engineer, "crew chief" the helicopter mechanic that kept it in the air, also manned one of the M60 machine guns on a "Slick", or other weaponry on a gunship
Central Highlands= a plateau area at the southern edge of the Truong Son Mountains, was a strategically important region of South Vietnam throughout the 1960s and 1970s. Constituted most of I and II Corps Field Forces AO. Nearly one million people, primarily Montagnard tribesmen, lived in the 20,000 square miles of the Central Highlands in 1968. The region was economically known for its production of coffee, tea, and vegetables.
Chicken Plate= chest protector (body armor) worn by helicopter pilots and gunners, sometimes gunners sat on their chicken plate to protect other vital parts
Chinook= the CH-47, twin rotor, cargo helicopter; also called "Shithook" or "Hook"
Chogie, "Cut A Chogie"= to move out very quickly; a term brought to Vietnam by soldiers who had served in Korea
Choi Oi= (pronounced "choy oye") Vietnamese term, exclamation like "holy cow," or "What the hell!"
CIB= The Combat Infantry Badge was awarded only to combat veterans holding an infantry MOS and several award levels based on number of tours in a combat zone (meeting the base requirement each time)
CIDG= (pronounced "sidgee") Civilian Irregular Defense Group, often Montagnard or Vietnamese national guard types
Close Air Support= air strikes against enemy targets, usually by Air Force A-10 aircraft ("Wart Hog" due to its 'ugly' appearance), that are close to friendly forces, and requiring intimate contact and coordination between ground and air units
CO= commanding officer, often called "the old man"
Contact= in contact with the enemy, or firefight, also spotting a target or LZ from the air
Conex= a large metal military container about 6'x6'x7' tall, used for shipping military supplies and equipment, and more often for bunkers, showers, living in, etc.
CONUS= the continental United States of America, "state-side"
CP= command post where the unit operations center was located
C-Rations, Cs = canned rations issued to GIs for field operations, NOT very tasty
Crew Chief= the helicopter crewmember responsible to maintain the daily operational status of the aircraft, and in Hueys to fly along on all missions to fix mechanical problems and act as door gunner (usually left side of the AC)
CYA= cover your ass

DA= density altitude, the higher the DA the less lift a helicopter can achieve, because high DA corresponds to low air density, thus less lift on the rotor blades
DEROS= Date of Expected Return from Overseas, the date you were allowed to go home
Didi= Vietnamese for get away from me, or move out, or on the run
Didi Mau= Vietnamese for get away from me NOW!, rapidly
Dinks= Vietnamese, (actually a Korean word for "foreigner")
Dinky Dau= Vietnamese term for "crazy"
Di Wee= (pronounced "die-wee") Vietnamese for rank of captain
DMZ= demilitarized zone around the Seventeenth Parallel, the temporary division line between North and South Vietnam established by the Geneva Accords of 1954
DOD= Department of Defense
Donut Dolly= American Red Cross Volunteer - female, namesake of their World War I counterpart; supposed to help the morale of the troops
Dope= term for marijuana and other illegal drugs
Dustoff= a nickname for a medical evacuation helicopter or mission, also "Medevac"

E & E= Escape and Evasion
Elephant Grass= tall, sharp-edged grass found in the highlands of Vietnam, often reaching 6' tall or more making judgement of where the ground actually was very difficult for helicopter pilots, or troops jumping out of the chopper, and making booby traps in LZs very easy to conceal
Exfil, exfiltrate, exfiltration= to sneak out/pick up/extract ground personnel, or the point of exit from an AO
Extraction= withdrawal/removal by airmobile resources of troops from any AO

FAC= usually US Air Force Forward Air Controller, but sometimes Army fixed wing
Fast mover= a jet, usually an F-4 Fantom
Feet Wet= expression used by pilots to indicate they were over water, or directions from air traffic controllers to help locate AC on radar
FINI (pronounced "feeny" with emphasis on the Y)= French term for finished, to GIs it meant "I'm done!" or "I'm outta here!"
Firebase= a remote artillery position, usually quite isolated with airlift support the main means of resupply
Flack Jacket= heavy fiberglass-filled vest worn for protection from light shrapnel primarily, different from the "chicken plate" in that it was worn as a vest and it was flexible, not rigid ceramic and metal
FNG= f---ing new guy
Free Fire Zone= an area in which US troops could shoot at any target they identified as hostile without prior permission (which became very few after about 1969) and was designated for "clearing weapons" on the AC to make sure they were working properly
Freq= radio frequency
Friendlies= U.S. troops, allies, ARVN, or anyone not on the enemy side
FUBAR= short for "F---ed Up Beyond All Recognition" to describe really bad situations, equipment, people, or mission directives from higher HQ

Gooks= derogatory term for Vietnamese soldiers, and often civilians too
GPM= gallons per minute fuel consumption
Grease Gun= M3/M3A1 sub-machinegun, .45 caliber automatic weapon
"GRUNT"= affectionate name for Infantry type soldiers or "ground pounders" - stands for "ground replacement usually not trained"
Gunner= helicopter crew member acting as machine gunner, could be almost anyone, but most often an AC mechanic still learning the job

Hanoi Hilton= nickname American prisoners of war used to describe the Hoa Loa Prison in Hanoi, North Vietnam
Heat Tabs= fuel pellets about the size of a half-dollar that burned slowly and were used for heating C-Rations, or other purposes
HHC= headquarters and headquarters company of a battalion or higher unit
Hootch= house, native hut, or GI living quarters
Horn= term for radio, or landline telephone ("Get Intruder 6 on the horn.")
HQ= any headquarters unit, also where ever the CO is located
Huey= the Bell UH-1 "Iroquois" helicopter, generally configured with a 1,400 shaft horse power (SHP) Avco Lycoming engine, with a cruising speed of about 100 knots and a range of 300 miles, the workhorse of the Vietnam airmobile war
Hump= to trudge around on foot, also carry something heavy like an M60 machine gun

I Corps (pronounced "eye core")= northernmost military region in South Vietnam beginning around Danang and going to the DMZ, headquarters of I Corps was located in Danang
II Corps (pronounced "two core")= area of operations just south of I Corps from south of Danang to south of Cam Ranh Bay
III Corps (pronounced "three core")= from south of Cam Ranh Bay to north of Saigon
IV Corps (pronounced "four core")= southern tip of South Vietnam located in the Mekong River Delta to north of Saigon
Incoming= receiving enemy mortar or rocket fire on your position
INTEL= intelligence information, also G-2
IP= instructor pilot, authorized to certify other pilots as flight ready

Jesus Nut= main rotor retaining nut that holds the main rotor onto the rest of the rotor mast, so name because if it came off only Jesus could help you survive
Jolly Green Giant= an Air Force HH-53 heavy rescue helicopter, or also a heavily armed Air Force C-47 aircraft supporting troops

Klick, "K"= a kilometer, the U.S. military map metric measure equal to 1,000 meters or about .6 mile
"Knots"= nautical miles per hour used for stating military aircraft airspeed
KIA= killed in action

Lai Dai (pronounced "la day")= Vietnamese for "come here"
LZ= landing zone "Hot" LZ= one active with enemy fire, or expected fire
        LZ Prep= "prepare" an LZ for landing aircraft and troops by suppressing enemy action through gunship rocket and machine gun fire, artillery bombardment, Air Force fighter jet heavy weapons, and even on rare occasions Navy ship bombardment from off-shore
        LZ, "Cut an"=  using a large bomb (500lb or more) with a 6" long protruding fuse, a C-130 aircraft would fly over an AO and "cut" an LZ because the bomb would explode horizontally, not creating a crater but clearing vegetation and debre, bombs were also referred to as "Daisy cutters" since they only cleared the ground's surface
LRRP= long range reconnaissance patrol, generally Special Forces Green Berets, also applied to Marines - pronounced "lurp"
LRRPs= in jargon "lurps" also applied to the freeze dried rations that LRRP patrols were issued, light weight, mix with water (hot preferably) and eat - VERY TASTY!

US Army carbine rifle, semi-automatic firing .30 caliber bullet, mostly used in Korea but a few were still found in Vietnam
M-14= US Army rifle, semi-automatic firing 7.62mm bullet initially used in Vietnam, but replaced by the M-16
= US Army rifle, semi-automatic & fully automatic firing a 5.56mm bullet
M-60= US Army machine gun firing a 7.62mm bullet at aprox. 550 rounds per minute
MAC-SOG= Military Assistance Command Studies and Observation Group, mission of covert operations in SEA
MACV= (pronounced "Mac-vee") Military Assistance Command, Vietnam
Mama-San= an older Vietnamese woman who usually was employed to do laundry and clean hootches
McGuire Rig= special harness and rope device for lifting ground troops out of a dense jungle canopy by helicopter, named after the inventor SGM McGuire
Medevac= medical evacuation of injured/wounded personnel often by Medevac helicopter units, also called "Dust Off"
MIA= missing in action, a soldier whose body was not recovered, or not confirmed KIA
Mic (pronounced "mike")= microphone
Mike(s)= minute(s)
Mike Force, MSF= Special Forces Mobile Strike Force; composed of US and indigenous troops, and used as a reaction or reinforcing unit
Montagnard= one of the indigenous mountain tribes people of Southeast Asia (usually pronounced 'mountainyard' by GIs, or just 'yards')
MPC= Military Payment Certificate, used in lieu of cash or dollars in Vietnam, also "funny money"

Napalm= highly flammable explosive used by Air Force fast-movers to burn up an area of suspected enemy activity, or lay down a barrier between friendlies and enemy
NEWBIE= any person with less time in Vietnam than the person speaking to them
Newbie WOJG (pronounced "wo-gee")= brand new Warrant Officer "Junior Grade" generally meaning WO1 with no-time-in-grade
Nuoc Mam= fermented fish sauce used for cooking and spicing Vietnamese food, made by drying fish on racks in the sun, which created a smell that could permeate 1000' altitude and could make most GIs puke
NVA= North Vietnamese Army soldiers/units

OD= "olive drab" color, standard Army issue green color, also, Officer of the Day

P-38= GI issue can opener for canned C-rations
Papa-San= an older Vietnamese man who usually was employed to do general labor around a compound including filling sandbags, and cleaning latrines
Piaster, "P"= monetary unit of RVN, generally bills, coins were called "dong"
PBO= property book officer
PIC= pilot in command, different from AC in that PIC was whoever was senior between the two pilots and had not yet received official unit designation as AC
PP, "Peter Pilot"= affectionate name for a co-pilot who generally was too inexperienced to be considered of much use other than to change radios, watch AC gauges, and maybe follow the map
Poncho liner= light camouflage colored nylon insert to the military rain poncho, generally used as a blanket
Pop Smoke= to mark a team sight location, or LZ, or target with a colored smoke grenade, then a pilot would ID the color to ensure the right location
POW= Prisoner of War, something to avoid at all cost
PRC-25 (called "prick 25") lightweight infantry field FM radio, the PRC-77 version incorporated an encryption feature for secure communication
Pucker Factor= gauge of the level of fear or anxiety in the risk or difficulty in a mission
Puff the Magic Dragon= an Air Force AC-47 aircraft fitted with side-firing miniguns and flares to support night operations and defense of enemy attacks on firebases

R&R= rest and recuperation, generally out-of-country for most people (Hawaii or Thailand), but the "grunts" could get a little R&R in-country just by NOT being in the field
Radios= FoxMike - FM (frequency modulation, low band width Infantry compatible)
        UHF - Ultra high frequency (Air Force, Navy and ATC compatible frequencies)
        Victor - VHF - very high frequency (Army command and control frequencies, ship-to-ship communication and local control tower communication)
RECON= reconnaissance
REMF= Rear Echelon Mother F---er, derogatory name for those serving in the safer rear areas, given freely to many types of positions by front-line soldiers
Revetment= the parking place for helicopters
RoadRunner Team= team of about 5-6 Green Berets and ARVNs that went in secretly to scout/recon and were extracted secretly - if possible
ROKs= Republic of Korea soldiers/units WHRID= White Horse ROK Infantry Division
RON= "remain over night," or somewhere other than your own hooch/bed/cot
RTO= radio telephone operator who carried the PRC-25, or any radio operator
RPG= rifle-propelled grenade, Russian-manufactured antitank grenade launcher

Sappers= North Vietnamese Army or Vietcong demolition commandos who infiltrated friendly compounds and planted explosives
SEA= South East Asia, meaning all of that area (not just South Vietnam), including Laos, Cambodia, North Vietnam, etc.
SHADOW= C-119 gunship with 7.62mm and/or 20mm mini guns mounted in side windows.
Short= number of days left until DEROS, going home, even FNGs were 364 days "short"
Short Final= aircraft preparing to land within a minute at an airfield or in an LZ
Single-Digit Midget= a person who was "so short" to DEROS that they only had single digit days left
Sin Loi (pronounced "sin loy")= Vietnamese for "too bad," or "tough sh_t" often followed by other descriptive expletives
SIT-REP= situation report
Slick= helicopter used to carry troops or cargo with only self protective armaments, see Huey Slick above
Slope= a derogatory term used to refer to Asians
Snake= the AH-1 Cobra gunship built specifically for armored attack
Sniffer Missions= slicks configured with ammonia sensory devices attached to the skids would low-level above the canopy very slow to detect high levels of ammonia from urine as an indication that enemy troops were, or had been in the area
Snoopy Missions= a mission flown often where one ship flew at tree-top level, trying to draw enemy fire from hidden troops, and the gun ships at higher elevation would locate the enemy and dive and attack
SOG= Studies and Observations Group, also, Special Operations Group
Sortie= one aircraft takeoff and landing to conduct a mission
Spooky= a C-47 gunship with 7.62 mini guns mounted in the side windows
Stand-Down= the unit is ordered to rest, re-outfit, and repair for future operations, during which time all operational activity, except for security, is ceased
StarLight Scope= night-vision telescope, used by snipers and basecamp defense troops to see in the dark
Strap Hanger= a term that comes from the Airborne meaning someone who is not a regular member of the unit or operation but is just along for the ride

Tailboom= the back end of a Huey just behind the engine compartment
TOC= Tactical Operations Center, pronounced "tock" also called "flight ops" the place in an Avn. Co. where flight missions are generally assigned and posted, a daily and nightly stopping place for crew members
Tracer= a bullet that leaves a visible trail from its phosphorus tip as it travels, usually red
Triple canopy= thickest jungle with vegetation growing at 3 levels; ground level, intermediate, and high levels
Trung Wee= Vietnamese for sergeant

USARPAC= United States Army, Pacific Command

VC= Viet Cong (Vietnamese guerillas, local militia basically)

WP, "Willie Pete"= a white phosphorus artillery round, rocket or grenade that explodes phosphorus and burns whatever it contacts