| Abk. | Bedeutung | Kontext |
| O | Organization unit | X.400-Adressierung |
| OAGIS | Open Applications Group Integration Specifications | |
| ÖB | Der Österreichische Betriebswirt | |
| OC | Optical Carrier | |
| OCG | Österreichische Computer Gesellschaft | |
| OCR | Optical Character Recognition | |
| ODBC | Open Database Connectivity | |
| ODETTE | Organisation of Data Exchange and Teletransmission in Europe | |
| ODI | Open Data-Link Interface | |
| ODMG | Open Database Management Group | |
| OECD | Organization for Economic Cooperation and Development in Europe | |
| OEM | Original Equipment Manufacturer | |
| OFD | Oberfinanzdirektion | |
| OFL | Organization Forms Library | MS Exchange Server, Globale Formularbibliothek |
| OFL | Oberste Finanzbehörde der Länder | |
| OHG | Offene Handelsgesellschaft | |
| o.J. | ohne Jahr | |
| OLAP | Online Analytical Processing | Data Warehousing |
| OLE | Object Linking and Embedding | |
| OLED | Organic Light-Emitting Device | |
| OLG | Oberlandesgericht | |
| OMA | Object Management Architecture | |
| OMG | Object Management Group | UML |
| OML | Open Modeling Language | |
| OMT | Object Modeling Technique | |
| oo | objektorientiert | |
| o.O. | ohne Ort | |
| OOD | Object Oriented Design | |
| ooDM | objektorientiertes Datenmodell | |
| OP | Offene Posten | |
| OPEC | Organization of Petroleum Exporting Countries | |
| OPL | Oilfield Publications Limited | Unternehmen |
| ORDRSP | Order Response | EDIFACT |
| OS | Operating System | |
| OSD | Open Software Distribution | |
| OSF | Open Software Foundation | |
| OSI | Open Systems Interconnection | ISO |
| OSPF | Open Shortest Path First | OSI |
| OSS | Open Source Software | |
| OST | Offline Folder Store | MS Exchange Client, Offline-Ordner |
| OTC | Over-the-counter | Finanzmarkt |
| OTC | Offshore Technology Conference | Erdölindustrie |
| OU | Organisationseinheit | X.400-Adressierung |
| OVA | Overhead Value Analyses, Gemeinkosten-Wertanalyse | BWL |
| OWI | Organisations- und Wirtschaftsinformatik | |
| ÜSG | Überspannungsschutzgerät | |