| Abbreviation | Definition |
|---|---|
| OPSEC | Open Platform for Secure Enterprise Connectivity |
| OSD | Open Source Definition |
| OSE | Open Security Exchange |
| OSG | Operational Security Guidelines |
| OSN | Operator Security Number |
| OSP | Operator Security Password |
| OSSTMM | Open Source Security Testing Methodology Manual |
| OT | Open Trapdoor |
| OTAC | One-Time Authorization Code |
| OTAR | Over-The-Air Rekeying |
| OTKSL | One Time Key Subsidy Lock |
| OTX | Object Tool eXtended |
| OW | Ominous Worms |
| OWASP | Open Web Application Security Project |
| PA | Privacy Act |
| PAD | Private Alias Directory |
| PAIN | Privacy, Authentication, Integrity, and Non-repudiation |
| PAL | Personal Access List |
| PAPA | Privacy, Accuracy, Property, Accessibility |
| PAPB | Payment Application Best Practices |