| Abbreviation | Definition |
|---|---|
| OM | Ordem dos Mdicos |
| OM | Ordem dos Médicos |
| OM | Society of Physicians |
| OMA | Ontario Medical Association |
| OMADS | Orrell Musical And Dramatic Society |
| OMBKE | Hungarian Mining and Metallurgical Society |
| OMBKE | Országos Magyar Bányászati és Kohászati Egyesület |
| OMBKE | Orszgos Magyar Bnyszati s Kohszati Egyeslet |
| OMES | Otago Model Engineering Society |
| OMGS | Oklahoma Mineral and Gem Society |
| OMGS | Old Marlburian Golfing Society |
| OMRS | Olympic Model Railroad Society |
| OMS | Oklahoma Microscopy Society |
| OMS | One Mission Society |
| OMS | Oregon Mycological Society |
| OMSA | Orders and Medals Society of America |
| OMSS | Oxford Migration Studies Society |
| OMV | Ordem dos Mdicos Veterinrios |
| OMV | Ordem dos Médicos Veterinários |
| OMV | Order of Veterinary Doctors (Portugal) |