| Abbreviation | Definition |
|---|---|
| OPN | Other Procurement, Navy funding |
| OPNAV | Office of the Chief of NAVal OPerations |
| OPNAVINST | Chief of Naval Operations Instruction |
| OPNAVINST | Office of the Chief of Naval Operations INSTruction |
| OPNS | Operations |
| OPNS/OPS | Operations |
| OPO | Operational Performance Objective |
| OPORD | Operation Order |
| OPORD | Operations Order |
| OPOS | Operating Procedure Outline Sheet |
| OPP | Off-Load Preparation Party |
| OPP | Orderwire Patch Panel |
| OPPA | Operation Plan Package Appraisal |
| OPQ | German WW II Battlecruiser class, never built |
| OPR | Office of Primary Responsibility |
| OPR | Officer Performance Report |
| OPR | Operator |
| OPR | Organization of Primary Responsibility |
| OPREP | Operational Report |
| OPREP-1 | (message format used for OPORD) |