| Abbreviation | Definition |
|---|---|
| OTMA | Open Transaction Manager Access |
| OTN | Open Transport Network |
| OTP | One Time Password |
| OTS | Object Transaction Service |
| OU | Organizational Unit |
| OUF | Other-Users Factor |
| OUI | Open Usability Interface |
| OV | Ogg Vorbis |
| OVN | Open Virtual Networking |
| OVQ | Optimum Video Quality |
| OVQMS | Objective Video Quality Measurement System |
| OWA | Outlook Web Access |
| OWC | Office Web Component |
| OWM | Outdoor Wireless Mesh |
| P&E | Power and Equipment |
| P2P | Peer to Peer |
| P2P | Point-To-Point |
| PA | Port Adapter |
| PA | Presence Agent |
| PA1 | Pacific Atlantic 1 |