| COI | Comité Olímpico Internacional (www.olympic.org) = CIO | Comité International Olympique | In French = IOC | International Olympic Committee | In English = МОК | Международен олимпийски комитет | In Bulgarian = MOO | Međunarodni olimpijski odbor | In Bosnian = COI | Comitè Olímpic Internacional | In Catalan = MOV | Mezinárodní olympijský výbor | In Czech = IOK | Internationales Olympisches Komitee | In German = ΔΟΕ | Διεθνής Ολυμπιακή Επιτροπή | In Greek = IOK | Internacia Olimpika Komitato | In Esperanto = COI | Comité Olímpico Internacional | In Spanish = ROK | Rahvusvaheline Olümpiakomitee | In Estonian = KOK | Kansainvälinen olympiakomitea | In Finnish = MOO | Međunarodni olimpijski odbor | In Croatian = NOB | Nemzetközi Olimpiai Bizottság | In Hungarian = TOK | Tarptautinis olimpinis komitetas | In Lithuanian = IOC | Internationaal Olympisch Comité | In Dutch = IOK | (Den) internasjonale olympiske komité | In Norwegian = MKOI | Międzynarodowy Komitet Olimpijski | In Polish = COI | Comité Olímpico Internacional | In Portuguese = МОК | Международный олимпийский комитет | In Russian = MOK | Međunarodni olimpijski komitet | In Serbo-Croatian = MOV | Medzinárodný olympijský výbor | In Slovak = MOK | Mednarodni olimpijski komite | In Slovenian = МОК | Међународни олимпијски комитет | In Serbian = IOK | Internationella Olympiska Kommitté | In Swedish = МОК | Міжнародний олімпійський комітет | In Ukrainian |
In Galician | → Sport, physical exercises |
| COI | Comité Olímpico Internacional (www.olympic.org) = CIO, IOC, МОК, MOO, MOV, IOK, ΔΟΕ, ROK, KOK, NOB, TOK, MKOI, MOK (look above) |
In Spanish | → Sport, physical exercises |
| COI | Comitè Olímpic Internacional (www.olympic.org) = CIO, IOC, МОК, MOO, MOV, IOK, ΔΟΕ, ROK, KOK, NOB, TOK, MKOI, MOK (look above) |
In Catalan | → Sport, physical exercises |
| COI | Comité Olímpico Internacional (www.olympic.org) = CIO, IOC, МОК, MOO, MOV, IOK, ΔΟΕ, ROK, KOK, NOB, TOK, MKOI, MOK (look above) |
In Portuguese | → Sport, physical exercises |
| COJESKI | Collectif des Organisations des Jeunes Solidaires du Congo-Kinshasa | In French | |
| COMEXI | Consejo de Comercio Exterior e Inversiones | In Spanish | → Trade |
| COMI | Cooperazione per il Mondo in via di Sviluppo | In Italian | → Development |
| CompTIA | Computing Technology Industry Association | In English | → Associations → Computer science |
| COMRA | China Ocean Minerals Research and Development Association | In English | → Associations → Marine research, oceanography → Mining |
| ComSo | Communications Society | In English | → Telecommunications |
| CONAD | Congresso Nacional de Administração | In Portuguese | → Congresses → Public administration, government |
| CONAD | Consorzio Nazionale Dettaglianti | In Italian | → Trade |
| CONAP | Confederation of Amazonian Nationalities of Peru = CONAP | Confederación de Nacionalidades Amazónicas del Perú | In Spanish = CONAP | Confédération des Nationalités Amazoniennes du Pérou | In French = CONAP | Confederação das Nações Amazônicas do Peru | In Portuguese = ICISS | International Commission on Intervention and State Sovereignty | In English = CIISE | Commission Internationale de l'Intervention et de la Souveraineté des États | In French |
In English | |
| CONAP | Confederación de Nacionalidades Amazónicas del Perú = ICISS, CIISE (look above) |
In Spanish | |
| CONAP | Confederação das Nações Amazônicas do Peru = ICISS, CIISE (look above) |
In Portuguese | |
| CONAP | Confédération des Nationalités Amazoniennes du Pérou = ICISS, CIISE (look above) |
In French | |
| CONATEL | Consejo Nacional de Telecomunicaciones | In Spanish | → Telecommunications |
| CONFAPI | Confederazione Italiana della Piccola e Media Industria | In Italian | → Economic policy |
| CONFETRA | Confederazione Generale Italiana del Traffico e dei Trasporti | In Italian | → Transport and postal services |
| CONPIROM | Confederaţia Patronală din Industria Română | In English | → Industry, industrial policy |
| CoNPR | Consiliul Naţional al Patronilor din România | In Romanian | → Labour, labour economics |
| CONQUEST | Conference on Quality Engineering in Software Technology | In English | → Congresses → Software |
| CONVINCE | Consortium of North American Veterinary Interactive New Concept Education | In English | → Education → Veterinary medicine |
| COPANT | Comisión Panamericana de Normas Técnicas | In Spanish | → Standardization |
| COPE | Cooperazione Paesi Emergenti | In Italian | |
| CORAF | Conférence de Responsables de Recherche Agronomique Africains | In French | → Agricultural sciences |
| COREO | Consortium of Regional Ecological Observatories | In English | → Environment, environmental sciences → Ecology |
| CoRWM | Committee on Radioactive Waste Management (www.corwm.org.uk) | In English | → Nuclear technology → Environmental technology, water supply, waste management |
| COSI | Comité Ouvrier de Secours Immédiat | In French | |
| COSL | Comité Olympique et Sportif Luxembourgeois | In French | → Sport, physical exercises |
| COSOR | Comité des Œuvres Sociales de la Résistance | In French | → Social welfare → History |
| COSPE | Cooperazione per lo Sviluppo dei Paesi Emergenti | In Italian | |
| COSV | Comitato di coordinamento delle Organizzazioni per il Servizio Volontario | In Italian | |
| COTANCE | Confederation of National Associations of Tanners and Dressers of the European Community | In English | → Leather industry |
| COTSEAL | Council of Teachers of Southeast Asian Languages | In English | → Education → Language, linguistics, literature |
| COV | Centrum Ontmoeting der Volkeren | In Dutch | → Development |
| COV | Christelijke Ontspannings Vereniging | In Dutch | → Christianity → Sport, physical exercises |
| CPA | Canadian Psychological Association = SCP | Société Canadienne de Psychologie | In French |
In English | → Associations → Psychology |
| CPAP | Council of Provincial Associations of Psychologists = CSPP | Conseil des Sociétés Provinciales de Psychologues | In French |
In English | → Psychology |
| CPB | Corporation for Public Broadcasting (www.cpb.org) | In English | → Telecommunications |
| CPC | Canadian Pork Council (www.cpc-ccp.com) = CCP | Conseil Canadien du Porc | In French |
In English | → Agricultural sciences → Food technology |
| CPCET | Centre de Pharmacologie Clinique et d'Évaluations Thérapeutiques | In French | → Pharmacology, toxicology |
| CPIA | Canadian Plastics Industry Association (www.cpia.ca) | In English | → Associations → Plastic industry |
| CPMP | Committee for Proprietary Medicinal Products | In English | → Pharmacology, toxicology |
| CPO | College of Psychologists of Ontario | In English | → Psychology |
| CPRS | Czechoslovak Pattern Recognition Society | In English | → Computer-based techniques |
| CPS | Comunità Promozione e Sviluppo | In Italian | → Development |
| CRA | Centro Ricerche Astronomiche di Lecce (www.cralecce.net) | In Italian | → Research institutes → Astronomy |
| CRAC | Comité radicalement anti-corrida | In French | → Nature and society |
| CRAHM | Centre de Recherches Archéologiques et Historiques Médiévales (www.unicaen.fr/crahm/) | In French | → Research institutes → Archeology → History |
| CRAL | Coordination des Radios locales Associatives de Lorraine | In French | → Telecommunications |
| CRAN | Conseil Représentatif des Associations Noires | In French | → Social sciences |
| CRAPE | Centre de Recherche sur l'Action Politique en Europe | In French | → Research institutes → Sociology → Politics |
| CRC | Cytology Research Centre | In English | → Research institutes → Cytology |
| CRCI | Chambre Régionale de Commerce et d'Industrie | In French | → Industry, industrial policy |
| CRCIL | Centre de Recherche Cardiovasculaire INSERM-Lariboisière | In French | → Research institutes → Blood and circulatory system → Cardiology |
| CRE | Conférence des Recteurs Européens | In French | → Higher education, universities |
| CREA | Canadian Real Estate Association | In English | → Associations → Accommodation |
| CREATIS | Centre de Recherche et d'Application en Traitement de l'Image et du Signal | In French | → Research institutes → Graphical processing → Image processing |
| CREM | Centre de Recherche en Économie et Management | In French | → Research institutes → Economics → Management |
| CRIC | Centro Regionale d'Intervento per la Cooperazione | In Italian | |
| CRIM | Centre de Recherche en Ingénierie Multilingue (www.crim.fr) | In French | → Research institutes → Language, linguistics, literature |
| CRIN | Centre de Recherche en Informatique de Nancy | In French | → Research institutes → Computer science |
| CRL | Communication Research Laboratory | In English | → Research institutes → Telecommunications |
| CRMV-RJ | Conselho Regional de Medicina Veterinária do Rio de Janeiro | In Portuguese | → Veterinary medicine |
| CRN | Comparative Research Network | In English | → Research policy |
| CRN | Conselho Regional de Nutricionistas | In Portuguese | → Nutrition |
| CRN | Collaborative Research Network | In English | → Research policy |
| CRP | Comité Régional de Pêche | In French | → Fishing, hunting |
| CRP | Clubul Român de Presa | In Romanian | → Newspapers, journalism |
| CRPCC | Centre de Recherches en Psychologie, Cognition et Communication | In French | → Research institutes → Psychology → Sociology |
| CRPL | Cosmic Ray Physics Laboratory | In English | → Research institutes → Astronomy → Physics |
| CRRL | Centre Régional Résistance et Liberté | In French | → Museums → History |
| CRS | Controlled Release Society (www.controlledrelease.org) | In English | → Pharmacology, toxicology |
| CRWAD | Conference of Research Workers in Animal Diseases | In English | → Veterinary medicine |
| CSA | Casting Society of America (www.castingsociety.com) | In English | → Cinema, movies |
| CSA | California Sociological Association | In English | → Associations → Sociology |
| CSA | Conseil Supérieur de l'Audiovisuel | In French | → Cinema, movies → Telecommunications |
| CSA | Canadian Soccer Association | In English | → Associations → Sport, physical exercises |
| CSAA | Canadian Sociology and Anthropology Association | In English | → Associations → Sociology |
| CSAUS | Chinese School Association in the United States | In English | → Associations → Education → Language, linguistics, literature |
| CSB | Christelijke Sportclub Baflo | In Dutch | → Christianity → Sport, physical exercises |
| CSBA | Canadian Swine Breeders Association (www.canswine.ca) | In English | → Associations → Agricultural sciences |
| CSC | Confédération des Syndicats Chrétiens = ACV | Algemeen Christelijk Vakverbond | In Dutch |
In French | → Labour, labour economics → Christianity |
| CSCA | Christelijke Sport Club Actief | In Dutch | → Christianity → Sport, physical exercises |
| CSCI | Centre for the Study of Contemporary Islam | In English | → Research institutes → Islam |
| CSCMP | Council of Supply Chain Management Professionals | In English | → Maintenance and logistics |
| CSCS | Centre for the Study of Culture & Society | In English | → Research institutes → Civilization, culture, progress → Social sciences |
| CSD | Centrale des Syndicats Démocratiques | In French | → Labour, labour economics |
| CSDL | Charles Stark Draper Laboratory | In English | → Research institutes |
| CSDR | Confederaţia Sindicatelor Democratice din România | In Romanian | → Labour, labour economics |
| CSE | Council of Science Editors | In English | → Mathematics and natural sciences → Graphic industries, printing, publishing |
| CSEM | Centre Sismologique Européen-Méditerranéen (www.emsc-csem.org) | In French | → Research institutes → Seismology, earthquakes |
| CSHSP | Collectif de Soutien des Homos Sans Papiers | In French | → 3472 |
| CSI | Cité des Sciences et de l'Industrie | In French | → Museums → Mathematics and natural sciences → Applied sciences, technology |
| CSI | Civil Society International | In English | |
| CSI-CSIF | Confederación de Sindicatos Independientes y Sindical de Funcionarios | In Spanish | → Labour, labour economics |
| CSIC | Consejo Superior de Investigaciones Científicas | In Spanish | → Mathematics and natural sciences |
| CSIR | Council for Scientific and Industrial Research | In English | → Research policy |
| CSIRO | Commonwealth Scientific and Industrial Research Organization (www.csiro.au) | In English | → International relations → Research policy → Engineering, technology |
| CSIS | Conseil Stratégique des Industries de Santé | In English | → Medicine → Pharmacology, toxicology |
| CSL | Combinatie Sport Leeuwarderadeel | In Dutch | → Sport, physical exercises |
| CSOEC | Conseil Supérieur de l'Ordre des Experts-Comptables | In French | → Commercial law → Accounting |
| CSP | Conseil Supérieur de la Pêche | In French | → Fishing, hunting |
| CSP | Comité des Spécialités Pharmaceutiques | In French | → Pharmacology, toxicology |
| CSPP | Conseil des Sociétés Provinciales de Psychologues = CPAP (look above) |
In French | → Psychology |
| CSPT | Conference for the Study of Political Thought | In English | → Politics |
| CSRI | Conference on the Study of Religions of India | In English | → Indian religions |
| CSRP | Chambre Syndicale de la Répartition Pharmaceutique | In French | → Pharmacology, toxicology |
| CSSIN | Conseil Supérieur de la Sûreté et de l’Information Nucléaire | In French | → Nuclear technology |
| CSTA | Chambre Syndicale du Transport Aérien | In French | → Transport and postal services |
| CSTEP | Comité Scientifique, Technique et Économique de la Pêche | In French | → Fishing, hunting |
| CSTI | Conseil Stratégique des Technologies de l’Information | In French | → Computer science → Telecommunications |
| CSTO | Collective Security Treaty Organization | In English | → International relations |
| CSV | Christelijke Sport Vereniging | In Dutch | → Christianity → Sport, physical exercises |
| CSV | Castricumse Sport Vereniging | In Dutch | → Sport, physical exercises |
| CSVA | Confederate States Vexillological Association | In English | → Associations → 9299 |
| CSVC | Christelijke Sport Vereniging Coevorden | In Dutch | → Christianity → Sport, physical exercises |
| CSVD | Christelijke Sportclub Vitesse Delft | In Dutch | → Christianity → Sport, physical exercises |
| CSVH | Christelijke Sport Vereniging Hoogkerk | In Dutch | → Christianity → Sport, physical exercises |
| CSW | Combinatie Sportclub Wilnis | In Dutch | → Sport, physical exercises |
| CTAA | Centre Technique d'Aide aux Associations | In French | → Associations → Applied sciences, technology |
| CTBTO | Comprehensive Nuclear-Test-Ban Treaty Organization | In English | → International relations → Nuclear technology |
| CTC | Congrès du Travail du Canada = CLC | Canadian Labour Congress | In English |
In French | → Labour, labour economics |
| CTI | Cooling Technology Institute Home (www.cti.org) | In English | → Applied sciences, technology |
| CTI | Commission des Titres d’Ingénieur (www.cti-commission.fr) | In French | → Specialized or (poly)technical colleges |
| CTL | Component Test Laboratory | In English | → Research institutes |
| CTL | Canoga Test Laboratory | In English | → Research institutes |
| CTP | Centre Technique du Papier (www.webctp.com) | In French | → Research institutes → Paper and board industry |
| CTSB | Cape Town Society for the Blind (www.ctsb.co.za) | In English | |
| CTSIS | Coordinamento per la Tutela del Settore Intrattenimento e Spettacolo | In Italian | → Entertainment |
| CULLT | Club des Utilisateurs des Logiciels Libres en Tunisie | In French | → Software |
| CUMA | Coopérative d'Utilisation du Matériel Agricole | In French | → Agricultural sciences |
| CUMA | Coopérative d’Utilisation de Matériel Agricole | In French | → Agricultural sciences |
| CUQ | Confederazione Unitaria dei Quadri | In Italian | → Labour, labour economics |
| CURE | Connecticut United for Research Excellence (www.curenet.org) | In English | → Biological sciences → Medicine |
| CUTO | Club des Utilisateurs d'Orphée | In French | → Libraries |
| CVAH | Centrale Vereniging voor Ambulante Handel | In Dutch | → Trade |
| CVBVB | Christelijke Voetbal Vereniging Bedum | In Dutch | → Christianity → Football and rugby |
| CVC | Compascuumer Voetbal Club | In Dutch | → Football and rugby |
| CVCS | Centro Volontari Cooperazione allo Sviluppo | In Italian | → Development |
| CVDC | Cambridge Vehicle Dynamics Consortium | In English | → Vehicle engineering |
| CVM | Centro Volontari Marchigiani | In Italian | |
| CVM | Christian Veterinary Mission (www.cvmusa.org) | In English | → Christianity → Veterinary medicine |
| CVMA | Canadian Veterinary Medical Association (www.canadianveterinarians.net) | In English | → Associations → Veterinary medicine |
| CVO | College of Veterinarians of Ontario (www.cvo.org) | In English | → Veterinary medicine |
| CVO | Combinatie Vrouwenparochie Oude Leije | In Dutch | → Sport, physical exercises |
| CVSB | Christelijke Voetbalvereniging Scheemder Boys | In Dutch | → Christianity → Football and rugby |
| CVV | Charloise Voetbal Vereniging | In Dutch | → Football and rugby |
| CVVA | Christelijke Voetbal Vereniging Arnhem | In Dutch | → Christianity → Football and rugby |
| CVVO | Christelijke Vereniging Voor Ontspanning | In Dutch | → Christianity → Sport, physical exercises |
| CVW | Christelijke Voetbalclub Winschoten | In Dutch | → Christianity → Football and rugby |
| CWC | Concerned for Working Children | In English | → Labour, labour economics → Fundamental rights |
| CWIN | Child Workers in Nepal | In English | → Labour, labour economics → Fundamental rights |
| CWL | Center for Women's Leadership (www3.babson.edu/cwl/) | In English | → Feminism |
| CWL | California Women Lawyers (www.cwl.org) | In English | → Law, jurisprudence |
| CWL | Catholic Women's League of Canada (www.cwl.ab.ca) | In English | → Roman catholic church |
| D | Delegito | In Esperanto | |
| DA | Dansk Arbejdsgiverforening | In Danish | → Labour, labour economics |
| DAG | Deutsche Angestellten Gewerkschaft | In German | → Labour, labour economics |
| DAGM | Deutsche Arbeitsgemeinschaft für Mustererkennung | In German | → Associations → Computer-based techniques |
| DAGV | Deutsche Arbeitsgemeinschaft Genealogischer Verbände | In German | → Associations |
| DAHW | Deutsche Lepra- und Tuberkulosehilfe | In German | → Pathology |
| DAL | Droit au Logement | In French | → Accommodation |
| DALTO | De Aanval Leidt Tot Overwinning | In Dutch | → Sport, physical exercises |
| DAMA | Data Management Association (www.dama.org) | In English | → Associations → Knowledge management → Data |
| DARA | Deutsche Agentur für Raumfahrtangelegenheiten | In German | → Astronomy → Spaceflight engineering, astronautics |
| DAV | Deutscher Astrologen Verband (www.dav-astrologie.de) | In German | → Occult sciences |
| DAV | Deutscher Altphilologenverband (www.altphilologenverband.de) | In German | → Semiotics |
| DAV | Deutscher Apotheker Verlag (www.deutscher-apotheker-verlag.de) | In German | → Pharmacology, toxicology |
| DAV | Deutsche Aktuarvereinigung (www.aktuar.de) | In German | → Law, jurisprudence |
| DAV | Deutscher Anglerverband (www.anglerverband.com) | In German | |
| DAV | Deutscher Anwaltverein (www.anwaltverein.de) | In German | → Law, jurisprudence |
| DAV | Deutscher Alpenverein (www.alpenverein.de) | In German | |
| DAVO | Dordrecht Aan Vallen en Overwinnen | In Dutch | → Sport, physical exercises |
| DAW | De Aanhouder Wint | In Dutch | → Sport, physical exercises |
| DAWG | Data Access Working Group | In English | → Data → Networks, communication |
| DBB | Deutscher Beamtenbund | In German | → Labour, labour economics → Public administration, government |
| DBC | Dordtse Boys Combinatie | In Dutch | → Sport, physical exercises |
| DBG | Deutsche Bodenkundliche Gesellschaft (www.dbges.de) | In German | → Agricultural sciences |
| DBGC | Don Bosco Grijsoord Combinatie | In Dutch | → Sport, physical exercises |
| DBH | Dart Bezirksverband Hannover | In German | → Sport, physical exercises |
| DBK | Door Broederschap Krachtig | In Dutch | → Sport, physical exercises |
| DBLA | Don Bosco Lay Association | In English | → Associations → Roman catholic church |
| DBS | Door Broederschap Sterk | In Dutch | → Sport, physical exercises |
| DBSV | Don Bosco Studenten Vereniging | In Dutch | → Sport, physical exercises |
| DBU | Deutsche Buddhistische Union | In German | → Buddhism |
| DBV | Door Bevrijding Verkregen | In Dutch | → Sport, physical exercises |
| DCG | Door Combinatie Groot | In Dutch | → Sport, physical exercises |
| DCL | De Charloise Leeuw | In Dutch | → Sport, physical exercises |
| DCO | Door Combinatie Overwinning | In Dutch | → Sport, physical exercises |
| DCS | Door Combinatie Sterk | In Dutch | → Sport, physical exercises |
| DCTB | Deutscher Christlicher Techniker-Bund | In German | → Christianity → Labour, labour economics |
| DCV | Door Combinatie Verkregen | In Dutch | → Sport, physical exercises |
| DCVMA | District of Columbia Veterinary Medical Association | In English | → Associations → Veterinary medicine |
| DDD | Den Danske Dyrlægeforening (www.ddd.dk) | In Danish | → Agricultural sciences |
| DDG | Deutsche Diabetes Gesellschaft | In German | → Physiology → Pathology |
| DDH | De Drie Hoefijzers | In Dutch | → Sport, physical exercises |
| DDV | Deutscher Direktmarketing Verband | In German | → 659 |
| DDV | Deutscher Dart-Verband | In German | → Sport, physical exercises |