| Abbreviation | Definition |
|---|---|
| OJCS | Office of Joint Chiefs of Staff |
| OJF | Operation Joint Forge, Bosnia |
| OJR | Operation Just Relief |
| OJT | On The Job Training |
| OK | Operation Klar |
| OK | Zero Killed |
| OKH | Charles O'Neil, Elmer Keith, and Don Hopkins (30-06 ammunition type) |
| OKH | OberKommando der Heers |
| OKU | Organized Killing Unit |
| OKW | OberKommando der Wehrmacht |
| OL | Operating Location |
| OLA | Ontario Liberation Army |
| OLB | Overpass Light Brigade |
| OLD | On-Line Tests and Diagnostics |
| OLE | Organizational Leadership for Executives course - Army CGSC |
| OLF | Outlying Landing Field |
| OLOS | Optical Line-of-Sight |
| OLOS | ptical Line-of-Sight |
| OLP | On-Line Provisioning |
| OLQ | Officer-Like Qualities |