| Abbreviation | Definition |
|---|---|
| BOU | British Ornithologists' Union |
| BPSU | Bermuda Public Services Union |
| BPSU | Bristol Polytechnic Student's Union |
| BPSU | Buddhism and Psychology Student Union |
| BRFU | Brunei Rugby Football Union |
| BRFU | Buller Rugby Football Union |
| BRU | Bus Riders Union |
| BRUI | Business Retail Union of Ireland |
| BSCU | Black Squirrel Credit Union |
| BSCU | Brooks Savings and Credit Union |
| BSCU | Broward Schools Credit Union |
| BSCU | Buckeye State Credit Union |
| BSCU | Buffalo Service Credit Union |
| BSOIW | International Association Of Bridge, Structural, Ornamental Reinforcing Iron Workers |
| BSOIW | International Association Of Bridge, Structural, Ornamental & Reinforcing Iron Workers |
| BSTU | BARBADOS SECONDARY TEACHERS Union |
| BSU | Barre Supervisory Union |
| BSWU | Boot and Shoe Workers' Union |
| BTAG | Bharat Transport Association Group |
| BTCU | Building Trades Credit Union |