| B |
| B | Bomber |
| BA | Base Area (VC/NVA) |
| BAARINC | Booze-Allen Applied Research, Inc. |
| Back | The individual occupying the back seat of the F-4; in Navy called RIO, in Air Force called pilot or GIB. |
| BAR | Browning Automatic Rifle |
| BARCAP | Barrier combat air patrol - a MIGSCREEN for one or more missions. |
| Barrel Roll | 360 degree rolling maneuver in which the flight path of the aircraft describes a helix about the-intended direction of the flight |
| BAS | Basic Allowance for Subsistence |
| BB | Battleship |
| Bbl/BBL | Barrel(s) |
| BC | Transportation Barge |
| BCAT | Battalion Combat Assistance Team |
| BCCR | Border Control Center Regions |
| BCE | Base Civil Engineer/Engineering |
| BCE | Bulk Construction Equipment |
| BCM | Base/Bulk Construction Material |
| BCT | Basic Combat Training |
| BDA | Bomb Damage Assessment |
| Bde/BDE | Brigade |
| BEQ | Bachelor Enlisted Men's Quarters |
| BEQ | Barrack Enlisted Quarters |
| BER | Budget Executive Review |
| BG/BGEN | Brigadier General |
| BIAS | Battlefield Illumination Airborne System |
| BIG MACK | Viet Cong Infrastructure Periodic Report |
| BIIL | Basic Issue Item List |
| BINGO (fuel) | Minimum fuel quantity reserve established for a given geographical point to permit aircraft to return safely to home base or aerial refueling point. |
| Binh Van | "Action against the enemy troops." This was a program of the National Liberation Front to degrade and demoralize the enemy's armed forces - the troop proselyting program. |
| Binh Vram | Equivalent to a logistics regiment headquarters |
| Black Pony | OV- 10 Twin Engine Turboprop Counter-Insurgency Aircraft |
| BLDG | Building |
| BLSG | Brigade Logistic Support Group |
| BLT | Battalion Landing Team |
| BM | Boatswainmate |
| BMT | Basic Military Training |
| Bn/BN | Battalion |
| BNDD | Bureau of Narcotics and Dangerous Drugs |
| BNH | Bien Hoa |
| BNR | Body Not Recovered |
| BOA | Basic Ordering Agreement |
| BOBS | Beacon Only Bombing System-Seek Point |
| BOC | Barrier Operations Center |
| BOC | Bureau of Customs |
| BOD | Beneficial Occupancy Date(s) |
| Bogey | Unidentified aircraft |
| BOH | Balance on Hand |
| BOM | Bill of Materials |
| BOP | Bill of Projects |
| BOQ | Bachelor Officers' Quarters |
| Boresight mode | In the boresight mode the radar antenna is aligned and locked to the roll axis of the aircraft. |
| BPO | Base Post Office |
| BPO | Budget Project Officer |
| BPS | Balanced Pressure System |
| BR | BARREL ROLL |
| BR | Body Recovery |
| Br | Branch |
| Break | Emergency turn in which maximum performance is desired instantly to destroy an attackers tracking solution. |
| Break X | Minimum range indication for missile launch. X appears in the radar scope at minimum range. |
| BRIAM | British Advisory Mission |
| Brig Gen | Brigadier General |
| BRJ | Brown-Root-Jones |
| BS | Bachelor or Science |
| BSA | Base Support Area |
| BSB | Budget Screening Board |
| BSM | Bronze Star Medal |
| BT | Binh Tram (Enemy Logistical Command and Control Agency) |
| Btry/BTRY | Battery |
| BTV | Big Test Vehicle |
| BTY | Binh Tuy |
| BUDC | Barrio United Defense Corps |
| Bufe | Vietnamese Ceramic Elephant |
| BUMED | Bureau of Medicine |
| BW | Boston Whaler |