| Abbreviation | Definition |
|---|---|
| OTV | Outer Tactical Vest |
| OTW | On The Water |
| OTW | Over The Waves |
| OU | Organizational Unit |
| OUB | Offshore Petroleum Discharge System (OPDS) Utility Boat |
| OUI | Officer under investigation |
| OUI | Organizational Unit Identifier |
| OUO | Official Use Only |
| OUSD | Office of the Under Secretary of Defense |
| OUSD(AT&L) | Office of The Under Secretary of Defense (Acquisition, Technology, and Logistics) |
| OUSD(C) | Office of The Under Secretary of Defense (Comptroller) |
| OUSD(P) | Office of The Under Secretary of Defense (Policy) |
| OUT | Operational Unit Transportable |
| OUT | Outsize Cargo |
| OUTBOARD | Shipboard organic collection, analysis, processing, DF, and Reporting System |
| OV | ObserVation aircraft |
| OV | Ohio Volunteers |
| OV | Operetional View |
| OV-1 | Mohawk ObserVation aircraft |
| OV-10 | Bronco ObserVation aircraft |