| Abbreviation | Definition |
|---|---|
| OCME | Office of the Chief Medical Examiner |
| OCOA | Ontario Conservation Officers Association |
| OCPA | Office of Communications and Public Affairs |
| OCPA | Oklahoma Council of Public Affairs |
| OCR | Orange County Register |
| OCRMS | Orange County Ramp Metering System |
| OCRMS | Orange County Ramp Metering System |
| OCRR | Office of Community Revitalization and Reinvestment |
| OCTA | Orange County Transportation Authority |
| OCTO | Orange County Transporter Organization |
| OCVFA | Onondaga County Volunteer Firemen's Association |
| OCY | Office for Children and Youth |
| OD | Old Dominion |
| ODA | Oklahoma Department of Agriculture |
| ODA | Oregon Department of Agriculture |
| ODACC | Ontario Dispute Adjudication for Construction Contracts |
| ODB | Ontario Drug Benefit |
| ODC | Ontario Development Corporation |
| ODE | Ohio Department of Education |
| ODE | Oregon Department of Education |