BSO
- Atos
- Baloch Students Organization
- Baltimore Symphony Orchestra
- Bank of Syria and Overseas
- Barents Sea Opening
- Basco Airport
- Basildon railway station
- Basilian Salvatorian Order
- Basque Statistics Office
- Beijing Symphony Orchestra
- Berliner Sinfonie Orchester
- Bilkent Symphony Orchestra
- Birmingham Symphony Orchestra
- Bismuth silicon oxide
- Black September Organization
- Bloomington Symphony Orchestra (Minnesota)
- Boston Symphony Orchestra
- Bournemouth Symphony Orchestra
- Brain storm optimization algorithm
- Brake Standard Open
- British School of Osteopathy
- British Society of Otology
- British Symphony Orchestra
- Broward County Sheriff's Office
- Buso language
- Buthionine sulfoximine
- Classifying space for SO
- Classifying space for SO(n)
- Glossary of cycling
- The Brian Setzer Orchestra
- Österreichische Bundes-Sportorganisation