| | ood | | object-oriented design |
| | OOE | | out of endurance |
| | OOF | | Out Of Facility |
| | OOF | | Out Of the Office |
| | OOFTW | | Out of this World |
| | OOIE | | Object-Oriented Information Engineering |
| | oop | | object oriented programming |
| | oop | | out of power |
| | oop | | out of print |
| | OOS | | Out of Stock |
| | OOTFPITF | | Out of the frying pan into the fire |
| | OOTO | | Out Of The Office |
| | OOTO | | out of the ofice |
| | OOTQ | | Out Of The Question |
| | OOTT | | Out on the town |
| | opac | | on-line payment and collection |
| | opac | | online public access catalogues |
| | OPEC | | Organization of Petroleum Exporting Countries |
| | OPUSH | | OBEX Object Push |
| | OPV | | Offshore Patrol vessels |
| | ORV | | Off Road Vehicle |
| | OSD | | Object Based Storage Device |
| | OSD | | Object Storage Device |
| | OSD | | On Screen Display |
| | OSD | | On-Screen Display |
| | OSEK | | Open systems and the Corresponding Interfaces for Automotive Electronics |
| | OSH | | Occupational Safety and Health Administration |
| | osha | | occupational safety and health administration |
| | OSIT | | On-Site Inspection Team |
| | OSU | | Officially Sanctioned User |
|