| Abbreviation | Description |
| NEA | Nuclear Energy Agency |
| NEGL | negligible |
| NGA | National Geospatial-Intelligence Agency |
| NIB | Nordic Investment Bank |
| NIC | newly industrializing country |
| NIE | newly industrializing economy |
| NIS | new independent states |
| nm | nautical mile |
| NMT | Nordic Mobile Telephone |
| NSG | Nuclear Suppliers Group |
| Nuclear Test Ban | Treaty Banning Nuclear Weapons Tests in the Atmosphere, in Outer Space, and Under Water |
| NZ | New Zealand |
| OAPEC | Organization of Arab Petroleum Exporting Countries |
| OAS | Organization of American States |
| OAU | Organization of African Unity; see African Union |
| ODA | official development assistance |
| ODF | Official Development Finance |
| OECD | Organization for Economic Cooperation and Development |
| OECS | Organization of Eastern Caribbean States |
| OHCHR | Office of the United Nations High Commissioner for Human Rights |
| OIC | Organization of the Islamic Conference |
| OIF | International Organization of the French-speaking World |
| 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 |