| Abbreviation | Description |
| ONUB | United Nations Operation in Burundi |
| OOF | other official flows |
| OPANAL | Agency for the Prohibition of Nuclear Weapons in Latin America and the Caribbean |
| OPCW | Organization for the Prohibition of Chemical Weapons |
| OPEC | Organization of Petroleum Exporting Countries |
| OSCE | Organization for Security and Cooperation in Europe |
| Ozone Layer Protection | Montreal Protocol on Substances That Deplete the Ozone Layer |
| PCA | Permanent Court of Arbitration |
| PDRY | People's Democratic Republic of Yemen [Yemen (Aden) or South Yemen]; used for information dated before 22 May 1990 or CY91 |
| PFP | Partnership for Peace |
| PIF | Pacific Islands Forum |
| PPP | purchasing power parity |
| Ramsar | see Wetlands |
| RG | Rio Group |
| SAARC | South Asian Association for Regional Cooperation |
| SACEP | South Asia Co-operative Environment Programme |
| SACU | Southern African Customs Union |
| SADC | Southern African Development Community |
| SAFE | South African Far East Cable |
| SCO | Shanghai Cooperation Organization |
| SECI | Southeast European Cooperative Initiative |
| SFRY | Socialist Federal Republic of Yugoslavia |
| SHF | super-high-frequency |