| B/L | Baseline |
| B/W | Black/White |
| BAA | Broad Agency Announcement |
| BAC | Budget At Completion |
| BAE | British Aerospace Engineering |
| BAMS | Bulletin of the American Meteorological Society |
| BAT | Baseline Acceptance Test |
| BAT | Bench Acceptance Test |
| BB | Blackbody |
| BB | Black Box |
| BB | Brassboard |
| BBC | Bus Baseband Console |
| BCD | Binary Code Decimal |
| BCD | Battery Charger/Discharger |
| BCH | Bose, Chaudhuri, and Hocquenghem error correcting code |
| BCN | Baseline Change Notice |
| BCP | Best Current Practice |
| BCR | Baseline Change Request |
| BCR | Build Content Review |
| BCWP | Budgeted Cost of Work Performed |
| BCWS | Budgeted Cost of Work Scheduled |
| BD | Basic Dvorak |
| BEI | Baseline Execution Index |
| BERB | Battery Enable Relay Box |
| BETA | Harris Proprietary Program |
| BFFC | Bit Flip Flush Cucles |
| BFM | Basic Fault Management |
| BER | Bit Error Rate |
| BG | background |
| BGITF | Boeing Geospatial Imagery Transformation Network |
| BGP | Border Gateway Protocol |
| BGSE | Bus Ground Support Equipment |
| BIRT | Business Intelligence and Reporting Tool |
| BIT | Built In Test |
| BITE | Built In Test Equipment |
| BLM | Block Level Metadata |
| BM | Bi-Monthly |
| BMGR | Baseline Manager |
| BNCF | Backup Network Control Facility |
| BNL | Brookhaven National Laboratory |
| BOC | Break of Configuration |
| BOE | Basis of Estimate |
| BOL | Beginning Of Life |
| BOM | Bill of Materials |
| BOM | Business Operations Manual |
| bps | bits per second |
| BPSK | bi-phase shift key |
| BRDF | Bi-directional Reflectance Distribution Function |
| BRF | Bi-directional Reflectance Factor |
| BRF | Body Reference Frame |
| BRTS | Biateration Ranging Transponder System |
| BS | Beam Splitter |
| BSD | Berkeley Software Distribution |
| BSM | Business Service Management |
| BSP | Board Support Package |
| BSRN | Baseline Surface Radiation Network |
| BSS | Block Started by Symbol |
| BSS | Boeing Space Systems |
| BT | Brightness Temperature |
| BTD | Brightness Temperature Difference |
| BTO | Business Technology Optimization |
| BTX | Balanced Technology Extended |
| BU | Business Unit |
| BUSIO | Bus Input/Output (FSW CSC) |
| BV | Brightness Value |
| BW | bandwidth |
| BW | Bi-weekly |
| BY | Budget Year |