| OMT | Object-Modeling Technique | In English | |
| OntoUCP | Ontology based Unified Communication Protocol | In English | → Networks, communication |
| OntoUCP | Ontology-based Unified Communication Protocol | In English | → Programming languages |
| OPML | Outline Processor Markup Language | In English | → Programming languages |
| ORDI | Ontology Representation and Data Integration | In English | |
| OS | Operating Software | In English | |
| OS | Operating System | In English | → Operating systems |
| OS3B | Open Software Blanc Bleu Belge | In French | → Organizations and associations |
| OSCR | Orbiter Software Change Request | In English | → Spaceflight engineering, astronautics |
| OSDL | Open Source Development Labs | In English | |
| OSDL | Open Source Development Lab | In English | |
| OSF | Open Software Foundation | In English | → Foundations |
| OSI | Open Source Initiative | In English | |
| OSID | Operating System Interface Definition | In English | → Operating systems → Human-computer interaction |
| OSIM | Open Source In Morocco | In English | → Organizations and associations |
| OSRBD | Operational Software Reliability Benchmark Development | In English | |
| OWL | Web Ontology Language | In English | → Data → Programming languages |
| PASO | Pattern-Oriented Software Architecture | In English | |
| PASS | Primary Avionics Software System | In English | → Aeronautics, aircraft |
| PASTISS | Professional Analysis Software Tool for Inflatable Space Structures | In English | → Mechanical engineering |
| PauLLA | Pau Logiciels Libres Association | In French | → Associations → Operating systems |
| PBIC | Programmable Buffer Interface Card | In English | → Hardware |
| PBIM | Programmable Buffer Interface Module | In English | → Human-computer interaction |
| PBS | Portable Batch System | In English | → Networks, communication |
| PC&PM | Program Control and Performance Management | In English | |
| PCGI | Perl Common Gateway Interface | In English | → Programming languages → Networks, communication |
| PCL | Programming Checklist | In English | |
| PCRE | Perl-Compatible Regular Expression | In English | |
| PCS | Professional Clinical Software | In English | → Medicine |
| Portable Document Format | In English | → Programming languages → Data → Document processing |
|
| PERL | Practical Extraction and Report Language | In English | → Programming languages |
| PESSL | Parallel Engineering and Scientific Subroutine Library | In English | → Programming languages → Mathematics and natural sciences → Engineering, technology |
| PFS | Primary Flight Software | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| PGC | Progiciel de Gestion du Contenu | In French | → Knowledge management |
| PGI | Progiciel de Gestion Intégrée | In English | |
| PGML | Precision Graphics Markup Language | In English | → Programming languages → Image processing |
| PHP | PHP Hypertext Preprocessor | In English | → Programming languages → Networks, communication |
| PHP | Personal Home Page | In English | → Programming languages → Networks, communication |
| PLDI | Programming Language Design and Implementation | In English | → Programming languages |
| PLUG | Provence Linux Users Group | In English | → Operating systems |
| PMAC | Portable Multipurpose Applications Console | In English | → Human-computer interaction |
| POJO | Plain Old Java Object | In English | → Programming languages |
| POSIX | Portable Operating System Interface | In English | → Human-computer interaction |
| PPCP | Postprocessing Computer Program | In English | |
| PPM | Perl Package Manager | In English | |
| PRAI | Pattern Recognition and Artificial Intelligence | In English | |
| PROGRESS | Programme for Research on Embedded Systems & Software | In English | → Electronics |
| PROLOG | PROgrammation LOGique | In French | → Programming languages |
| PRPS | Programming Requirements Process Specification | In English | |
| PS | PostScript | In English | → Programming languages → Document processing |
| PSL | Program Statement Language | In English | → Programming languages |
| PSO | Phantasy Star Online | In English | → Entertainment |
| PSP | Programmable Signal Processor | In English | → Telecommunications |
| QDOS | Quick and Dirty Operating System | In English | → Operating systems |
| QOM | Quick Ontology Mapping | In English | |
| RACF | Resource Access Control Facility | In English | |
| RADOP | Radiator Optimization Computer Code | In English | |
| RASMUS | Remote Accessible Software configurable Multi-channel Ultrasound Sampling system | In English | → Diagnostics |
| RCP | Rich Client Platform | In English | |
| RCP | Rémunération pour Copie Privée | In French | → Cinema, movies |
| RCS | Revision Control System | In French | |
| RDA | Rich Desktop Application | In English | |
| RDDL | Resource Directory Description Language | In English | → Programming languages → Data |
| RDM | Real-Time Data Manager | In English | → Data |
| RDOS | Real-Time Disk Operating System | In English | → Operating systems |
| REX | Remote Events for XML | In English | → Networks, communication |
| RFCP | Request For Computer Program | In English | |
| RFI | Remote File Inquiry | In English | |
| RGC | Retro-Gaming Connexion | In English | → Entertainment |
| RIA | Rich Internet Applications | In English | → Networks, communication |
| RIA | Rich Internet Application | In English | → Networks, communication |
| RICP | Real-Time Interactive Computer Program | In English | |
| RIS | Rauminformationssystem | In German | → Geography |
| RNTL | Réseau National des Technologies Logicielles | In French | → Organizations and associations |
| RNTL | Réseau National de Recherche et d'Innovation en Technologies Logicielles | In French | |
| ROSES | Rockwell Operational Software Engineering System | In English | |
| RSCS | Remote Spooling and Communication Subsystem | In English | → Networks, communication |
| RTCPS | Real-Time Computer Program System | In English | |
| RTCS | Real-Time Computer System | In English | → Hardware |
| RTFSS | Real-Time Flight Safety Software | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| SaaS | Software as a Service | In English | → Networks, communication |
| SACS | Software Avionics Command Support | In English | → Aeronautics, aircraft |
| SALUG | Savoie-Aravis Linux Users Group | In English | → Organizations and associations → Operating systems |
| SAML | Security Assertion Markup Language | In English | → Programming languages |
| SAS | Software Automation Subpanel | In English | |
| SAS | Software Approval Sheet | In English | |
| SASCB | Shuttle Avionics Software Control Board | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| SASTP | Stand-Alone Self-Test Program | In English | |
| SBML | Systems Biology Markup Language | In English | → Programming languages → Biological sciences |
| SBO | Systems Biology Ontology | In English | → Programming languages → Knowledge management → Libraries → Biological sciences |
| SC | Software Change | In English | |
| SCA | Software Command Analysis | In English | |
| SCATS | Sydney Co-ordinated Adaptive Traffic System | In English | → Transport and postal services |
| SCB | Software Control Board | In English | |
| SCCB | Software Change Control Board | In English | |
| SCCB | Software Configuration Control Board | In English | |
| SCCH | Software Competence Center Hagenberg (www.scch.at) | In English | |
| SCDR | Software Critical Design Review | In English | |
| SCI | Software Customer Inspection | In English | |
| SCM | Software Configuration Management/Manager | In English | |
| SCMO | Software Configuration Management Office | In English | |
| SCMP | Software Configuration Management Plan | In English | |
| SCOS | Subsystem Computer Operating System | In English | → Operating systems |
| SCR | Software Change Request | In English | |
| SCRB | Software Configuration Review Board | In English | |
| SCS | Solutions Communicantes Sécurisées | In French | → Networks, communication → Telecommunications |
| SCSL | Scientific Computing Software Library | In English | |
| SDBC | Software Development Baseline Control | In English | |
| SDC | Software Development Computer | In English | → Hardware |
| SDD | Software Design Document | In English | |
| SDD | Software Description Document | In English | |
| SDDD | Software Detailed Design Document | In English | |
| SDDL | Software Design and Document Language | In English | |
| SDE | Software Development Environment | In English | |
| SDF | Software Development File | In English | |
| SDF | Software Development Facility | In English | |
| SDH | Software Development Handbook | In English | |
| SDIF | Software Development and Integration Facility | In English | |
| SDK | Software Development Kit | In English | |
| SDL | Software Development Library | In English | |
| SDL | Software Development Laboratory | In English | → Research institutes |
| SDL | Simple Directmedia Layer | In English | |
| SDN | Software Development Note | In English | |
| SDP | Software Development Plan | In English | |
| SDR | Software Design Review | In English | |
| SDR | Software Design Requirement | In English | |
| SDRB | Software Design Review Board | In English | |
| SDS | Software Design Specification | In English | |
| SDVF | Software Development and Verification Facility | In English | |
| SE | Software Engineering | In English | |
| SE | Système d'Exploitation | In French | → Operating systems |
| SEAL | Software-Optimized Encryption Algorithm | In English | → Mathematics |
| SEAL | Semantics-directed Environment Adaptation Language | In English | → Programming languages |
| SEAL | Software Engineering and Ada Lab(oratory) | In English | → Research institutes |
| SEE | Software Equality Evaluation | In English | |
| SEE | Software Engineering Exercise | In English | |
| SEEL | Syndicat des Éditeurs de Logiciels de Loisirs | In French | → Organizations and associations |
| SEI | Software Engineering Institute | In English | |
| SELL | Syndicat des Éditeurs de Logiciel de Loisirs (www.sell.fr) | In French | → Organizations and associations → Entertainment |
| SELL | Syndicat des Éditeurs de Logiciel de Loisir (www.sell.fr) | In French | → Organizations and associations → Entertainment |
| SEM | SEmantic Memory | In English | → Semiotics |
| SES | Software Evaluation Subpanel | In English | |
| SEXI | String EXpression Interpreter | In English | → Programming languages |
| SFACI | Software Flight Article Configuration Inspection | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| SFLC | Software Freedom Law Center | In English | → Law, jurisprudence |
| SGML | Standard Generalized Markup Language | In English | → Programming languages → Data → Document processing |
| SI/FS | System Integration and Flight Software | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| SIA | Software Impact Assessment | In English | |
| SIG | Sistema Informativo Geografico = GIS | Geographic(al) Information System | In English = SIG | Sistema de Información Geográfica | In Spanish = SIG | Sistema d'informació geogràfica | In Catalan = GIS | Geografický Informační Systém | In Czech = ГИС | Географска информационна система | In Bulgarian = ΓΣΠ | Γεωγραφικά Συστήματα Πληροφοριών | In Greek = GIS | Geographisches Informationssystem | In German = GIS | Geoinformationssystem | In German = GIS | Geoinfosüsteem | In Estonian = GIS | Geografski informacijski sustav | In Croatian = ממ"ג | מערכת מידע גאוגרפית | In Hebrew = GIS | Geografinė informacinė sistema | In Lithuanian = SIG | Sistem Informasi Geografis | In Indonesian = GIS | Geografisch Informatiesysteem | In Dutch = GIS | Geografiske informasjonssystem | In Nynorsk = GIS | Geografiske informasjonssystemer | In Norwegian = SIG | Sistema de informação geográfica | In Portuguese = ГИС | Географическая Информационная Система | In Russian = GIS | Geografski informacijski sistem | In Slovenian = GIS | Geografiskt InformationsSystem | In Swedish = ГІС | Геоінформаційна система | In Ukrainian |
In Italian | → Geography |
| SIG | Sistema d'informació geogràfica = GIS, ГИС, ΓΣΠ, ממ"ג, ГІС (look above) |
In Catalan | → Geography |
| SIG | Sistem Informasi Geografis = GIS, ГИС, ΓΣΠ, ממ"ג, ГІС (look above) |
In Indonesian | → Geography |
| SIG | Sistema de informação geográfica = GIS, ГИС, ΓΣΠ, ממ"ג, ГІС (look above) |
In Portuguese | → Geography |
| SIG | Sistema de Información Geográfica = GIS, ГИС, ΓΣΠ, ממ"ג, ГІС (look above) |
In Spanish | → Geography |
| SIG | Système d'Information Géographique = TAC | Traitement Communautaire Assertif | In French = PACT | Program Assertif Community Treatment | In English |
In French | → Geography |
| SIGB | Système Intégré de Gestion de Bibliothèque = ILS | Integrated Library System | In English = АБИС | Автоматизированные библиотечные информационные системы | In Russian |
In French | → Knowledge management → Libraries |
| SIP | Software Input Panel | In English | |
| SIPB | Student Information Processing Board | In English | → Specialized or (poly)technical colleges |
| SIRR | Software Integration Readiness Review | In English | |
| SIRS | Système d'Information à Référence Spatiale | In French | → Geography |
| SIS | Software Implementation Specification | In English | |
| SIS | Software Integrated Schedule | In English | |
| SIT | Software Integrated Test | In English | |
| SIT | System Informacji o Terenie = SIT | Sistema Informativo Territoriale | In Italian = SIT | Système d'Information sur le Territoire | In French |
In Polish | → Regional planning → Geography |
| SIT | Sistema Informativo Territoriale = (look above) |
In Italian | → Regional planning → Geography |
| SIT | Système d'Information sur le Territoire = (look above) |
In French | → Regional planning → Geography |
| SLEE | Service Logic Execution Environment | In English | |
| SLPEM | Sparta Linear Programming Effectiveness Model | In English | |
| SLS | Softlanding Linux System | In English | → Operating systems |
| SMBL | Systems Biology Markup Language | In English | → Programming languages → Data → Biological sciences |
| SMIL | Synchronized Multimedia Integration Language | In English | → Programming languages → Computer-based techniques → Cinema, movies |
| SML | Spacecraft Markup Language | In English | → Programming languages → Spaceflight engineering, astronautics |
| SMP | Software Management Plan | In English | → Management |
| SMS | Software Modification Sheet | In English | |
| SMS | Site-Managed Software | In English | |
| SMSC | Software Moding, Sequencing, and Control | In English | |
| SMU | Software Management Utility | In English | |
| SNOBOL | StriNg Oriented symBOlic Language | In English | → Programming languages |
| SOMM | Software Operations and Maintenance Manual | In English | |
| SOP | Subsystem Operating Program | In English | |
| SP | Stored Procedure | In English | → Data |
| SPA | Software Product Assurance | In English | |
| SPC | Starting-Point Code | In English | |
| SPC | Stored Program Command | In English | |
| SPC | Stored Program Control | In English | |
| SPC | Software Productivity Consortium | In English | |
| SPCR | Software Problem Change Request | In English | |
| SPDR | Software Preliminary Design Review | In English | |
| SPE | Software Process Engineering | In English | |
| SPF | Software Production Facility | In English | |
| SPL | System Programming Language | In English | → Programming languages |
| SPM | Software Performance Monitor | In English | |
| SPM | Software Programmer's Manual | In English | |
| SPR | Software Problem Report | In English | → Quality management |
| SPS | Software Product Specification | In English | |
| SPS | Software Productivity Solution | In English | |
| SPT | System Planning Tool | In English | |
| SQA | Software Quality Assurance | In English | → Quality management |
| SQE | Software Quality Evaluation | In English | → Quality management |
| SRCB | Software Requirements Change Board | In English | |
| SRCBD | Software Requirements Change Board Directive | In English |