| Abbreviation | Definition |
|---|---|
| OCA | Offensive Counter Air |
| OCA | Offensive Counterair |
| OCA | Operational Control Authority |
| OCAR | Office of the Chief of Army Reserve |
| OCAR | Office of the Chief, Army Reserve |
| OCAR | Office, Chief Army Reserve |
| OCC | Operations Computer Center |
| OCCA | Ocean Cargo Clearance Authority |
| OCCH | Office of the Chief of Chaplains |
| OCD | Operational Concept Demonstration |
| OCD | Operational Concept Document |
| OCD | Orderwire Clock Distributor |
| OCDEFT | Organized Crime Drug Enforcement Task Force |
| OCE | Office of the Chief of Engineers |
| OCE | Officer Conducting The Exercise |
| OCEANCON | Control of Oceanographic Information |
| OCF | Officers' Christian Fellowship |
| OCF | Other Coalition Forces |
| OCHA | Office For The Coordination of Humanitarian Affairs |
| OCHR | Office of Civilian Human Resources |