| Abbreviation | Definition |
|---|---|
| BUG | Bicycle Users Group |
| BULA | Basic Ultra-Light Aeroplane |
| BYOB | Be Your Own Bartender |
| BYOB | Build Your Own Bag |
| BYOC | Bring Your Own Car |
| BYOF | Bring Your Own Fleet |
| BYOM | Bring Your Own Model |
| BYOT | Build Your Own Technology |
| BYOT | Build Your Own Tour |
| BYOZ | Bring Your Own Z-scale train |
| BYYB | Back Yard Yacht Builders |
| BYYC | BackYard Yacht Club |
| BZP | Bionicle Zone Power |
| C2C | Corner to Corner |
| CAAP | Canandians Against Apple Pie |
| CABS | Crappy Ace Bill Shipper |
| CAIF | Club Aerostatic de l'Isle de France |
| CAL | Casual Astronomy League |
| CALP | Carbohydrate Addicts Lifelong Program |
| CALS | Canadian Association For Leisure Studies |