AK-47 The Russian Kalashnikov rifle used by the Viet Cong
AO Area of operation to which soldiers were assigned
ARVN Army of the Republic of South Vietnam
AWOL Soldier who is away from his/her post without leave or permission
Bouncing Betty Cone-shaped mine that jumped about three feet in the air when triggered and exploded at waist level
C-4 Plastic explosive
Charlie or Chuck Slang expression for the enemy
Chicom Chinese Communist
CID Criminal Investigation Division
Claymore Mine Anti-personnel mine that projects shrapnel in a defined pattern
Cobra AG-1H assault helicopter
CS Tear gas used for riot control
Dust off Medivac-pickup of wounded personnel
EM Enlisted Man
F-4 Phantom jet
Flak Vest/Jacket Protective vest worn by U.S. military personnel
Grease Gun M-3 sub-machine gun
Grunts Slang for the infantry troops fighting on land
Gunship Helicopter equipped with machine guns and rockets
HE High explosive
Hooch/Hootch Small hut
Huey UH helicopter
Hump/Humpin Going on patrol in the bush/jungle; performing physical labor
KIA Killed in military action
LAW Light Assault or Light Anti-Tank Weapon
Leg Non-airborne military personnel who land with their legs straight rather than bent
LT Lieutenant
LZ Landing Zone
M-14 Heavy rifle issued to U.S. troops
M-16 Lighter, later rifle model issued to U.S. troops
M-60/The Pig Light belt-fed machine gun
M-79 Device to launch grenades
Mama San Older Vietnamese woman
NCO Non-Commissioned Officer; pay grades E-5 through E-9
NVA North Vietnamese Army
P-38 Folding metal can opener
Papa San Older Vietnamese male
PFC Private First Class
PRC-25 Portable FM Radio
PRC-77/The Monster Larger radio with a secure frequency
R&R Rest and recreation
Recon Reconnaissance, scouting mission
RPG/B-40 Rocket Propelled Grenade
RTO Radio Telephone Operator
Sin Loi Vietnamese slang for sorry, that’s too bad, or tough luck
SOP Standard Operating Procedure
Starlight scope Scope used to see at night
Toe Popper Plastic explosive designed to wound, not kill
VC Viet Cong; Vietnamese Communist
Willie Pete/WP White phosphorus grenade or artillery round
Zap Kill

Note: The definitions in the Military Jargon Defined are from the website, Vietnam and the Turbulent Times Dictionary and Gazetteer, with the permission of the site’s author, Gary D. Moore, SSgt USAF, a Vietnam Vet.