| Abbreviation | Definition |
|---|---|
| OBR | Our Band Rules |
| OBSN | Occaneechi Band of the Saponi Nation |
| OBW | Occupied Band Width |
| OBW | Optimal Band Width |
| OBZ | On Beyond Zebra |
| OC | O Canada |
| OCCB | Oakhurst Community Concert Band |
| OCCB | Ottawa Community Concert Band |
| OCCO | Oregon Coast Chamber Orchestra |
| OCFB | Original Cliff Boys |
| OCLB | Omer City Limits Band |
| OCM | Omaha Conservatory of Music |
| OCM | Openness Clarity And Musicality |
| OCMA | Obsessive Compulsive Music Awards |
| OCMB | Oberlin College Marching Band |
| OCML | Orange County Music League |
| OCP | Operador de Cabine Polivalente |
| OCSG | Orchestre des Concerts Symphoniques de Gatineau |
| OCSM | Orchestra e Coro San Marco |
| OCSM | Organization of Canadian Symphony Musicians |