| Abkürzung | Bereich | Staat | Bedeutung |
| N | Physik | Windungszahl | |
| n | Physik | Brechzahl | |
| Drehzahl | |||
| NASA | Institut | USA | National Aeronautics and Space Administration |
| NCA | Computer | Network Communications Adapter | |
| NDIS | Computer | Network Driver Interface Specification | |
| NDP | Computer | Numeric Data Processor | |
| NDS | Computer | Netware Directory Service | |
| NDX | Computer | Index | |
| NE | Computer | Network Element | |
| NEC | Firma | J | Nippon Electric Company |
| NEG | Mathematik | Negative | |
| NETBEUI | Computer | NETBIOS Extended User Interface | |
| NETBIOS | Computer | Network Basic Input / Output System | |
| NFS | Computer | Network File System | |
| NIC | Computer | Network Interface Card | |
| NK | Haus | D | Nebenkosten |
| NL | Computer | New Line | |
| NLM | Software | Netware Loadable Module | |
| NLS | Computer | National Language Support | |
| nm | Einheit | Nanometer | |
| NOR | Mathematik | Not Or (Nicht Oder) | |
| NOS | Computer | Network Operating System | |
| NPI | Computer | Network Printer Interface | |
| NPU | Computer | Natural Processing Unit | |
| NPX | Computer | Numeric Processor Extension | |
| NSA | Geheimdienst | USA | National Security Agency |
| NT | Allgemein | New Technology | |
| NTFS | Computer | New Technology File System | |
| NUA | Computer | Network User Address | |
| NUI | Computer | Network User Identification | |
| NV | Computer | No Overflow | |
| NVM | Computer | Non Volatile Memory | |
| NVR | Computer | Non Volatile RAM | |
| NVRAM | Computer | Non Volatile RAM | |
| o.ä. | Allgemein | D | oder ähnliches |
| OAI | Computer | Open Applications Interface | |
| OCL | Computer | Operation Control Language | |
| OCR | Computer | Optical Character Recognition | |
| OD | Computer | Oktal Dump | |
| ODAPI | Software | Open Database Application Programming Interface | |
| ODBC | Software | Open DataBase Connectivity | |
| ODBMS | Software | Object Oriented Database Management System | |
| ODC | Computer | Online-Data-Communication | |
| ODI | Computer | Open Datalink Interface | |
| Open Device Interconnect | |||
| ÖDP | Partei | D | Ökologisch-Demokratische Partei |
| ODS | Computer | Open Data Services | |
| OEM | Technik | Original Equipment Manufacturer | |
| OF | Computer | Overflow Flag | |
| OG | Haus | D | Obergeschoß |
| OLE | Computer | Object Linking and Embedding | |
| OLTP | Computer | Online Transaction Processing | |
| OMI | Computer | Open Messaging Interface | |
| ONC | Computer | Open Network Computing | |
| OOA | Computer | Object-Oriented Analysis | |
| OOD | Computer | Object-Oriented Design | |
| OODB | Computer | Object-Oriented Database | |
| OODMS | Computer | Object-Oriented Database Management System | |
| OOL | Computer | Object-Oriented Language | |
| OOP | Computer | Object-Oriented Programming | |
| OOPL | Computer | Object-Oriented Programming Language | |
| OOS | Computer | Object-Oriented Systems | |
| OP | Technik | Optical | |
| Output | |||
| Computer | Operator | ||
| Medizin | Oparation | ||
| Oparationssaal | |||
| OPM | Computer | Operations per Minute | |
| OPT | Computer | Open Protocol Technology | |
| OROM | Computer | Optical Read Only Memory | |
| OS | Computer | Operating System | |
| OSA | Computer | Open System Architecture | |
| OSF | Institut | USA | Open Software Foundation |
| OSI | Computer | Open Systems Interconnection | |
| OT | Computer | Object Technology | |
| OV | Computer | Overflow | |
| OWL | Software | Object Windows Library | |
| ÖZH | Haus | D | Ölzentralheizung |