| Abbreviation | Definition |
|---|---|
| OM | Operator Mechanic |
| OM | Organizational Manager |
| OMD | Office of Managing Director |
| OMD | Oriental Medical Doctor |
| OMEA | Office Manager/Executive Assistant |
| OMFS | Oral and MaxilloFacial Surgeon |
| OMH | Online Marketing Hero |
| OMT | Orthopaedic Manipulative Physiotherapist |
| OMW | Operation Michigan Works |
| ONC | Oncle ( French: Uncle) |
| ONE | Over Nearly Everyone |
| OOG | Olive Oil Guru |
| OOH | Occupational Outlook Handbook |
| OOLMI | Office of Occupational and Labor Market Information (Delaware) |
| OOR | Occupational Outlook Report |
| OOTE | Order of the Engineer |
| OOWE | Officer Of the Watch Engineer |
| OP | Official Photographer |
| OPA | Overseas Performing Artist |
| OPAC | Office Proficiency Assessment and Certification |