| Abbreviation | Definition |
|---|---|
| OM | Owner's Manual |
| OMA | Eppley Airfield |
| OMB | Offshore Model Basin |
| OMC | Office of Motor Carriers |
| OMC | Organisation Mondiale de Commerce |
| OMC | Overnite and Motor Cargo |
| OMCs | Office of Motor Carrier Standards |
| OMOT | Ohio Museum of Transportation |
| OMR | Old Mahabalipuram Road |
| OMT | Other Means of Transportation |
| OMVD | Odisha Motor Vehicle Department |
| ONER | Oceanic Navigational Error Report |
| ONR | ON Ramp |
| ONT | Ontario International Airport |
| ONT | Ontario Northland Transportation |
| OOG | Out Of Gear |
| OOPS | Outside Operating Pedestrian Sidewalk |
| OOS | Out Of Service |
| OPA | Oil Pollution Act of 1990 |
| OPC | Opel Performance Car |