| Abbreviation | Definition |
|---|---|
| OCR | Office of Collateral Responsibility |
| OCR | Operational Capability Requirement |
| OCR | Optical Character Recognition |
| OCS | Officer Candidate School |
| OCS | Operational Contract Support |
| OCSA | Office of the Chief of Staff, Army |
| OCSG | Operating Capability Study Group |
| OCSW | Objective Crew-Served Weapon |
| OCTU | Officer Candidate Training Unit |
| OCU | Officer's Christian Union |
| OCU | Operator Control Unit |
| OCU | Order wire Control Unit |
| OCU | Orderwire Control Unit (Types I, II, and III) |
| OCU-1 | Orderwire Control Unit-1 |
| OCW | On Camouflaged Wings |
| OD | Olive Drab |
| OD | On Duty |
| OD | Operational Detachment |
| OD | Operationally Determined |
| OD | Other Detainee |