| MIFAO | Mémoires publiés par les Membres de l'Institut francais d'Archéologie orientale | In French | → Serial publications, periodicals → Archeology |
| MIFAO | Mémoires de l'Institut Français d'Archéologie Orientale | In French | → Serial publications, periodicals → Archeology |
| MIFE | Maison(s) d'Information sur la Formation continue | In French | → Education |
| MII | Maisons Individuelles Isolées | In French | → Building → Energy economics |
| MILAD | Mission de Lutte Anti-Drogue | In French | → Public administration, government |
| MILS | Mission Interministérielle pour la Lutte contre les Sectes | In French | → 355 → Religion, theology |
| MIM | Maîtrise d'Ingénierie Mathématique | In French | → Higher education, universities → Mathematics → Engineering, technology |
| MIMOSA | Migration et Mobilité - Sémantique et Applications | In French | → Computer-based techniques → Telecommunications → Semiotics |
| MIN | Marché d'Intérêt National | In French | |
| MINEFI | MINistère de l'Économie et des FInances | In French | → Economics → Central administration |
| MINEFI | MINistère de l’Économie, des Finances et de l’Industrie | In French | → Central administration → Economics → Finance → Industry, industrial policy |
| MINES | Méthodes INnovantes pour l’Entreprise et la Société | In French | |
| MINUK | Mission Intérimaire d’administration des Nations Unies au Kosovo | In French | → United Nations |
| MIOM | Mâchefer d'Incinération d'Ordures Ménagères | In French | → Environmental technology, water supply, waste management |
| MIP | Mouvement pour l'Initiative Populaire | In French | → Political parties and movements |
| MIRE | Mesure et système d’Information des Réseaux Électriques | In French | → Electrical engineering |
| MIRE | MIssion Régionale de Revitalisation Économique | In French | → Regional administration → Economics → Regional planning |
| MIRES | Mission Interministérielle de Recherche et d'Enseignement Supérieur | In French | → Public administration, government → Education → Mathematics and natural sciences |
| MIRIADE | Mission Régionale pour l’Innovation et l’Action de Développement Économique | In French | → Research policy → Regional administration → Industry, industrial policy |
| MISASHS | Mathématiques, Informatique et Statistiques Appliquées aux Sciences Humaines et Sociales | In French | → Computer science → Social sciences → Statistics → Mathematics |
| MISE | Mission InterServices de l'Eau | In French | → Public administration, government → Hydrology |
| MIVILUDES | Mission interministérielle de vigilance et de lutte contre les dérives sectaires | In French | → 355 → Religion, theology |
| MJS | Mouvement de Jeunesse Sioniste | In French | → Organizations and associations → Judaism |
| MJS | Ministère de la Jeunesse et des Sports | In French | → Central administration → Sport, physical exercises |
| MLE | Maximum Likelihood Estimation | In French | → Computer science → Mathematics |
| MLF | Mouvement de Libération des Femmes | In French | → Organizations and associations → Feminism |
| MLI | Modulation de Largeur d'Impulsion | In French | → Electrical engineering |
| MLN | Mouvement de Libération Nationale | In French | → Organizations and associations → History |
| MMAI | Monuments et Mémoires publiés par l'Académie des Inscriptions et Belles-Lettres | In French | → Serial publications, periodicals |
| MmEbr | Mémoires de l'Observatoire de l'Ebre | In French | → Serial publications, periodicals → Astronomy |
| MMIL | Mouvement Missionnaire Intérieur Laïque | In French | → Modern spiritual movements |
| MMM | Myélofibrose avec Métaplasie Myéloïde | In French | → Blood and circulatory system → Pathology |
| MMT | Médecins Maîtres-Toile | In French | → Networks, communication → Organizations and associations → Medicine |
| Mn | Manganese = Mn | Mangaan | In Estonian = Mn | منجنيز | In Arabic = Mn | Manqan | In Azerbaijani = Mn | Mangan | In German = Mn | Манган | In Bulgarian = Mn | Manganès | In Friulian = Mn | Μαγγάνιο | In Greek = Mn | Manganeso | In Spanish = Mn | Mangano | In Esperanto = Mn | منگنز | In Persian = Mn | Manganese | In English = Mn | Mangaan | In Afrikaans = Mn | Mangan | In Bosnian = Mn | Manganès | In Catalan = Mn | Mangan | In Danish |
In French | → Chemistry |
| MNCP | Mouvement National des Chômeurs et Précaires | In French | → Organizations and associations → Labour, labour economics |
| MNEF | Mutuelle Nationale des Étudiants de France | In French | → Insurance → Education |
| MNR | Mouvement National Républicain | In French | → Political parties and movements |
| MO | Le Monde oriental | In French | → Serial publications, periodicals → Language, linguistics, literature → Geography, biography, history |
| MOCA | Modification des connaissances, attitudes et/ou comportements des usagers en faveur de la sécurité routière | In French | → Vehicle engineering → Transport and postal services |
| MOCF | Mutuelle de l'Orphelinat des Chemins de Fer Français | In French | → Transport and postal services |
| MOCI | Moniteur du Commerce International | In French | → Serial publications, periodicals → Trade |
| MOCN | Machine-Outil à Commande Numérique | In French | → Computer-based techniques → Mechanical engineering |
| MOI | Main d'Oeuvre Immigrée | In French | → Political parties and movements |
| MOM | MiddleWare Orienté Message | In French | → Computer science |
| MonAP | Communications du Département d'Astrophysique de la Faculté des Sciences de Mons | In French | → Serial publications, periodicals → Astronomy |
| MOUS | Maîtrise d'Oeuvre Urbaine et Sociale | In French | → Social welfare → Regional planning |
| MPA | Mouvement populaire de l’Azawad | In French | → Political parties and movements |
| MPA | Mouvement Pour l'Autodétermination | In French | → Political parties and movements |
| MPF | Mouvement Pour la France | In French | → Political parties and movements |
| MPH | Maison du Prêt d'Honneur | In French | → Accommodation → Higher education, universities |
| MPH | Master of Public Health | In French | → Higher education, universities → Public health and hygiene |
| MPI | Midi-Pyrénées Innovation | In French | → Regional administration → Engineering, technology |
| MPM | Marseille Provence Metropole | In French | → Public administration, government |
| MPOC | Maladie Pulmonaire Obstructive Chronique | In French | → Pathology |
| MRBT | Maintenance Réseaux-Bureautique-Télématique | In French | → Computer science → Telecommunications |
| MRC | Mouvement Républicain et Citoyen | In French | → Political parties and movements |
| MRCC | Modéle Régional Climatique Canadien | In French | → Meteorology, climatology |
| MRI | Ministère des Relations Internationales | In French | → Central administration → International relations |
| MRP | Mouvement Républicain Populaire | In French | → Political parties and movements |
| MRS | Mouvement Région Savoie | In French | → Political parties and movements |
| MSA | Mutualité Sociale Agricole | In French | → Insurance → Agricultural sciences |
| MSBM | Maîtrise de Sciences Biologiques et Médicales | In French | → Higher education, universities → Biological sciences → Medicine |
| MSF | Médecins Sans Frontières | In French | → Organizations and associations → Medicine |
| MSG | Maîtrise des Sciences de Gestion | In French | → Economics → Higher education, universities |
| MSIS | Modélisation, Simulation et Simulateurs de conduite | In French | → Transport and postal services |
| MSMA | Maintenance des Systèmes Mécaniques Automatisés | In French | → Maintenance and logistics → Mechanical engineering |
| MSP | Maîtrise Statistique des Procédés | In French | |
| MSR | Groupe Métallurgie Structure Rhéologie | In French | → Metallurgy |
| MSR | Mouvement Social Révolutionnaire | In French | → Political parties and movements |
| MST | Maîtrise des Sciences et Techniques | In French | → Higher education, universities → Mathematics and natural sciences → Applied sciences, technology |
| MST | Mission Scientifique et Technique | In French | → Mathematics and natural sciences → Applied sciences, technology |
| MSTCF | Maîtrise des Sciences et Techniques Comptables et Financières | In French | → Higher education, universities → Accounting |
| MT | Mises au Travail | In French | → Labour, labour economics |
| MTA | Mobilité et Transports Avancés | In French | → Transport and postal services |
| MTEV | Maladie Thromboembolique Veineuse | In French | → Blood and circulatory system |
| MTI | Mission des Transports Intelligents | In French | → Transport and postal services |
| MTP | Mesures Techniques de Protection | In French | |
| MTQ | Ministère des Transports du Québec | In French | → Central administration → Transport and postal services |
| MUB | Mélanges de l'Université Saint-Joseph de Beyrouth | In French | → Serial publications, periodicals |
| MUC | Mouvement de l'Utopie Concrète | In French | → Organizations and associations |
| MUNCI | Mouvement pour une Union Nationale des Consultants en Informatique | In French | → Computer science → Organizations and associations → 6592 |
| MUR | Mouvements Unis de la Résistance | In French | → Political parties and movements → History |
| MURCEF | Mesures Urgentes de Réformes à Caractère Économique et Financier | In French | → Economics → Public administration, government |
| MURF | Mouvement Unifié de la Renaissance Française | In French | → Political parties and movements |
| MUSJ | Mélanges (de la Faculté Orientale) de l'Université Saint-Joseph de Beyrouth | In French | → Serial publications, periodicals → Higher education, universities |
| MUST | Modélisation de l'Usage et de la Sécurité des Transports = MUST | Modelling the Use and Safety of Transport | In English |
In French | → Vehicle engineering → Transport and postal services |
| MVC | Modèle-Vue-Contrôleur | In French | |
| MVO | Maladie Veino-Occlusive | In French | → Pathology |
| MVO | Montreuil Ville Ouverte | In French | |
| N | Asparagine = N | Asparagine | In English = N | Asparagina | In Catalan = N | Asparagin | In German = N | Asparagina | In Spanish = N | Asparagino | In Esperanto = N | 아스파라긴 | In Japanese = N | Asparagin | In Indonesian = N | Asparagina | In Italian = N | אספרגין | In Hebrew = N | Asparagīns | In Latvian = N | Asparagin | In Letzeburgesh = N | Asparaginas | In Lithuanian = N | Asparagine | In Dutch = N | アスパラギン | In Japanese = N | Asparagina | In Polish = N | Asparagina | In Portuguese = N | Аспарагин | In Russian = N | Asparagín | In Slovak = N | Аспарагин | In Serbian = N | Asparagiini | In Finnish = N | Asparagin | In Swedish = N | Asparagin | In Turkish = N | Аспарагін | In Ukrainian = N | 天冬酰胺 | In Chinese |
In French | → Biochemistry, biophysics |
| N | Azote = N | Stikstof | In Afrikaans = N | نيتروجين | In Arabic = N | Nitróxenu | In Asturian = N | Azot | In Azerbaijani = N | Азот | In Belarusian = N | Азот | In Bulgarian = N | নাইট্রোজেন | In Bengali = N | Dušik | In Bosnian = N | Nitrogen | In Catalan = N | Azotu | In Corsican = N | Dusík | In Czech = N | Азот | In Chuvash = N | Nitrogen | In Welsh = N | Kvælstof | In Danish = N | Stickstoff | In German = N | Άζωτο | In Greek = N | Nitrogen | In English = N | Azoto | In Esperanto = N | Nitrógeno | In Spanish = N | Lämmastik | In Estonian = N | Nitrogeno | In Basque = N | نیتروژن | In Persian = N | Typpi | In Finnish = N | Azôt | In Friulian = N | Nítrigin | In Irish = N | Nitróxeno | In Galician = N | નાઇટ્રોજન | GU = N | Neetragien | GV = N | חנקן | In Hebrew = N | नाइट्रोजन | In Hindi = N | Dušik | In Croatian = N | Azòt | HT = N | Nitrogén | In Hungarian = N | Ազոտ | In Armenian = N | Nitrogeno | In Interlingua = N | Nitrogen | In Indonesian = N | Nitro | In Ido = N | Nitur | In Icelandic = N | Azoto | In Italian = N | 窒素 | In Japanese = N | trano | JBO = N | აზოტი | In Georgian = N | 질소 | In Korean = N | Stickstoff | KSH = N | Nîtrojen | In Kurdish = N | Nitrogenium | In Latin = N | Stéckstoff | In Letzeburgesh = N | Stikstof | LI = N | Azoti | In Lingala = N | Azotas | In Lithuanian = N | Slāpeklis | In Latvian = N | Hauota | In Māori = N | Азот | In Macedonian = N | നൈട്രജന് | In Malayalam = N | Азот | In Mongolian = N | नायट्रोजन | MR = N | Ehēcatehuiltic | En Nahuatl = N | Stickstoff | NDS = N | Stikstof | In Dutch = N | Nitrogen | In Nynorsk = N | Nitrogen | In Norwegian = N | Nitrogene | NOV = N | Azòt | In Occitan = N | Nitrogen | PAM = N | Azot | In Polish = N | Nitrogénio | In Portuguese = N | Qullpachaq | In Quechua = N | Azot | In Romanian = N | Азот | In Russian = N | Azzotu | In Sicilian = N | Dušik | In Serbo-Croatian = N | Dusík | In Slovak = N | Dušik | In Slovenian = N | Azoti | SQ = N | Азот | In Serbian = N | Kväve | In Swedish = N | Nitrojeni | In Swahili = N | நைட்ரஜன் | In Tamil = N | నత్రజని | TE = N | Азот | In Tajik = N | ไนโตรเจน | In Thai = N | Azot | In Turkish = N | Азот | In Ukrainian = N | Azot | In Uzbek = N | Nitơ | In Vietnamese = N | 氮 | In Chinese |
In French | → Chemistry |
| Na | Sodium = Na | Natrium | In Afrikaans = Na | صوديوم | In Arabic = Na | Sodiu | In Asturian = Na | Натрый | In Belarusian = Na | Натрий | In Bulgarian = Na | সোডিয়াম | In Bengali = Na | Natrijum | In Bosnian = Na | Sodi | In Catalan = Na | Sodiu | In Corsican = Na | Sodík | In Czech = Na | Sodiwm | In Welsh = Na | Natrium | In Danish = Na | Natrium | In German = Na | ސޯޑިއަމް | DV = Na | Νάτριο | In Greek = Na | Sodium | In English = Na | Natrio | In Esperanto = Na | Sodio | In Spanish = Na | Naatrium | In Estonian = Na | Sodio | In Basque = Na | سدیم | In Persian = Na | Natrium | In Finnish = Na | Sodi | In Friulian = Na | Sóidiam | In Irish = Na | Sodio | In Galician = Na | Sodjum | GV = Na | נתרן | In Hebrew = Na | सोडियम | In Hindi = Na | Natrij | In Croatian = Na | Sodyòm | HT = Na | Nátrium | In Hungarian = Na | Նատրիում | In Armenian = Na | Natrium | In Indonesian = Na | Natro | In Ido = Na | Natrín | In Icelandic = Na | Sodio | In Italian = Na | ナトリウム | In Japanese = Na | sodna | JBO = Na | Natrium | JV = Na | ნატრიუმი | In Georgian = Na | ಸೋಡಿಯಮ್ | KN = Na | 나트륨 | In Korean = Na | Natrîyûm | In Kurdish = Na | Natrium | In Latin = Na | Natrium | In Letzeburgesh = Na | Sodu | In Lingala = Na | Natris | In Lithuanian = Na | Nātrijs | In Latvian = Na | Konutai | In Māori = Na | Натриум | In Macedonian = Na | സോഡിയം | In Malayalam = Na | सोडियम | MR = Na | Natrium | NDS = Na | Natrium | In Dutch = Na | Natrium | In Nynorsk = Na | Natrium | In Norwegian = Na | Natrium | NOV = Na | Sôdgium | In Norman = Na | Sòdi | In Occitan = Na | Sód | In Polish = Na | Sódio | In Portuguese = Na | Natriyu | In Quechua = Na | Sodiu | In Romanian = Na | Натрий | In Russian = Na | Sodiu | In Sicilian = Na | Natrij | In Serbo-Croatian = Na | Sodík | In Slovak = Na | Natrij | In Slovenian = Na | Natriumi | SQ = Na | Натријум | In Serbian = Na | Natrium | In Swedish = Na | Natiri | In Swahili = Na | சோடியம் | In Tamil = Na | సోడియమ్ | TE = Na | Натрий | In Tajik = Na | โซเดียม | In Thai = Na | Sodyum | In Turkish = Na | Натрій | In Ukrainian = Na | Natriy | In Uzbek = Na | Natri | In Vietnamese = Na | Sodiom | In Walloon = Na | 钠 | In Chinese |
In French | → Chemistry |
| NABS | Nomenclature pour l'Analyse et la comparaison des Budgets et des programmes Scientifiques | In French | → Research policy |
| NACE | Nomenclature statistique des Activités économiques de la Communauté Européenne | In French | → Economics |
| NAF | Nomenclature d'Activités Française | In French | → Economics |
| NAN | Nombre Absolu de Neutrophiles | In French | → Blood and circulatory system |
| NANA | Acide N-acétylneuraminique = NeuAc | Acide N-acétylneuraminique | In French |
In French | → Biochemistry, biophysics |
| NAP | Noyautage des Administrations Publiques | In French | → Public administration, government → History |
| NAR | Nouvelle Action royaliste | In French | → Political parties and movements |
| NAUTILE | Noyau d'Aide à l'Usage, la Transmission et l'Installation des Logiciels libres sur l'Estuaire | In French | → Organizations and associations → Software |
| NCG | Neptune Club Gosselien | In French | → Organizations and associations → Sport, physical exercises |
| NCM | Négociations Commerciales Multilatérales | In French | → International economic cooperation |
| NEOM | Nutrition Énergétique des Organes et des Méridiens | In French | → Occult sciences |
| NERSA | (Société centrale) Nucléaire Européenne à neutrons Rapides SA | In French | → Nuclear technology → Electrical engineering |
| NeuAc | Acide N-acétylneuraminique = NANA (look above) |
In French | → Biochemistry, biophysics |
| NF | Norme Française (www.marque-nf.com) | In French | → Standardization |
| NH3 | Ammoniac | In French | → Chemistry |
| NMMBC | Neuropathie Motrice Multifocale à Bloc de Conduction | In French | → Neurology |
| NMPP | Nouvelles Messageries de la Presse Parisienne | In French | → Newspapers, journalism → Graphic industries, printing, publishing |
| NMR | Nouveau Mouvement Religieux = NRM | New Religious Movement | In English = NRB | Nieuwe Religieuze Beweging | In Dutch = NRJ | Naujieji religiniai judėjimai | In Lithuanian |
In French | → Modern spiritual movements |
| NOREX | Normes et Règlements à l'Export | In French | → Trade |
| NOx | Oxydes d'Azote | In French | → Chemistry |
| NPF | Nation la Plus Favorisée | In French | → Economics |
| NRA | Nœud de Raccordement Abonné | In French | → Telecommunications |
| NRA&A | Nouvelle Revue d'Aéronautique et d'Astronautique | In French | → Serial publications, periodicals → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| NRE | Nouvelles Régulations Économiques | In French | → Economics → Law, jurisprudence |
| NROA | Nouvelle Revue d'Optique Appliquée | In French | → Serial publications, periodicals → Optics |
| NROpt | Nouvelle Revue d'Optique | In French | → Serial publications, periodicals → Optics |
| NUMDAM | NUMérisation de Documents Anciens Mathématiques | In French | → Document processing → Libraries → Mathematics |
| nvMCJ | Nouveau variant de la Maladie de Creutzfeldt-Jakob | In French | → Neurology |
| O | Oxygène = O | Suurstof | In Afrikaans = O | Sauerstoff | ALS = O | أكسجين | In Arabic = O | Oxíxenu | In Asturian = O | Oksigen | In Azerbaijani = O | Sauastoff | BAR = O | Кісларод | In Belarusian = O | Кислород | In Bulgarian = O | অক্সিজেন | In Bengali = O | Oksigen | In Breton = O | Kiseonik | In Bosnian = O | Oxigen | In Catalan = O | Ossigenu | In Corsican = O | Kyslík | In Czech = O | Йӳçлĕк | In Chuvash = O | Ocsigen | In Welsh = O | Ilt | In Danish = O | Sauerstoff | In German = O | Οξυγόνο | In Greek = O | Oxygen | In English = O | Oksigeno | In Esperanto = O | Oxígeno | In Spanish = O | Hapnik | In Estonian = O | Oxigeno | In Basque = O | اکسیژن | In Persian = O | Happi | In Finnish = O | Ossigjen | In Friulian = O | Soerstof | In Frisian = O | Ocsaigin | In Irish = O | Àile-beatha | GD = O | Osíxeno | In Galician = O | ઑક્સીજન | GU = O | Ocsygien | GV = O | חמצן | In Hebrew = O | आक्सीजन | In Hindi = O | Kisik | In Croatian = O | Kislik | HSB = O | Oksijèn | HT = O | Oxigén | In Hungarian = O | Թթվածին | In Armenian = O | Oxygeno | In Interlingua = O | Oksigen | In Indonesian = O | Oxo | In Ido = O | Súrefni | In Icelandic = O | Ossigeno | In Italian = O | 酸素 | In Japanese = O | kijno | JBO = O | Oksigen | JV = O | ჟანგბადი | In Georgian = O | ಆಮ್ಲಜನಕ | KN = O | 산소 | In Korean = O | Sauerstoff | KSH = O | Oksîjen | In Kurdish = O | Oxygenium | In Latin = O | Sauerstoff | In Letzeburgesh = O | Zuurstof | LI = O | Oksijɛ́ní | In Lingala = O | Deguonis | In Lithuanian = O | Skābeklis | In Latvian = O | Hāora | In Māori = O | Кислород | In Macedonian = O | ഓക്സിജന് | In Malayalam = O | Хүчилтөрөгч | In Mongolian = O | ऑक्सिजन | MR = O | Oksigen | In Malay = O | Ehēcayoh | En Nahuatl = O | Suerstoff | NDS = O | अक्सिजन | NEW = O | Zuurstof | In Dutch = O | Oksygen | In Nynorsk = O | Oksygen | In Norwegian = O | Oxygen | OM = O | Oxygen | PAM = O | Tlen | In Polish = O | Oxigénio | In Portuguese = O | Muksichaq | In Quechua = O | Oxigen | In Romanian = O | Кислород | In Russian = O | Ossìgginu | In Sicilian = O | Kiseonik | In Serbo-Croatian = O | ඔක්සිජන් | SI = O | Kyslík | In Slovak = O | Kisik | In Slovenian = O | Oksigjeni | SQ = O | Кисеоник | In Serbian = O | Oksigén | SU = O | Syre | In Swedish = O | Oksijeni | In Swahili = O | ஆக்ஸிஜன் | In Tamil = O | ఆక్సిజన్ | TE = O | Оксиген | In Tajik = O | ออกซิเจน | In Thai = O | Oksiheno | In Tagalog = O | Oksijen | In Turkish = O | Кисень | In Ukrainian = O | Kislorod | In Uzbek = O | Ôxy | In Vietnamese = O | זויערשטאף | In Yiddisch = O | 氧 | In Chinese |
In French | → Chemistry |
| O3 | Ozone | In French | → Chemistry |
| OAEO | Organisation de l'Armement de l'Europe occidentale | In French | |
| OASIS | Objets Actifs, Sémantique, Internet et Sécurité | In French | → Networks, communication → Semiotics |
| OCA | Observatoire de la Côte d’Azur | In French | → Observatories |
| OCA | Ouest Convoyeur et Automatisme | In French | → Mechanical engineering |
| OCBC | Office Central de lutte contre le trafic des Biens Culturels | In French | → Police |
| OCDE | Organisation de Coopération et de Développement Économique (www.oecd.org) = OECD | Organisation for Economic Cooperation and Development | In English = OCDE | Organizaţia de Cooperare şi Dezvoltare Economică | In Romanian = ΟΟΣΑ | Οργανισμός Οικονομικής Συνεργασίας και Ανάπτυξης | In Greek = OESO | Organisasie vir Ekonomiese Samewerking en Ontwikkeling | In Afrikaans = OCDE | Organització per a la Cooperació i el Desenvolupament Econòmic | In Catalan = ОИСР | Организация за икономическо сътрудничество и развитие | In Bulgarian = OECD | منظمة التعاون والتنمية الاقتصادية | In Arabic = OESO | Organisatie voor Economische Samenwerking en Ontwikkeling | In Dutch = OEKE | Organizaĵo pri Ekonomiaj Kunlaboro kaj Evoluigo | In Esperanto = OCDE | Organización para la Cooperación y el Desarrollo Económico | In Spanish = KHEE | Kooperazio eta Hazkunde Ekonomikorako Erakundea | In Basque = OCDE | Organisation de cooperation e de developament economic | In Interlingue = OECD | 경제 협력 개발 기구 | In Korean = OECD | 経済協力開発機構 | In Japanese = OCSE | Organizzazione per la Cooperazione e lo Sviluppo Economico | In Italian = OECD | 经济合作与发展组织 | In Chinese = OECD | Tổ chức Hợp tác và Phát triển Kinh tế | In Vietnamese = OECD | องค์การเพื่อความร่วมมือทางเศรษฐกิจและการพัฒนา | In Thai = ОЭСР | Организация экономического сотрудничества и развития | In Russian = OCDE | Organização para a Cooperação e Desenvolvimento Económico | In Portuguese |
In French | → International relations → International economic cooperation |
| OCDPC | Office pour le Contrôle des Drogues et la Prévention du Crime = ODCCP | Office for Drug Control and Crime Prevention | In English |
In French | → United Nations → Criminal law |
| OCIM | Office de Coopération et d'Information Muséographiques | In French | → Museums |
| OCL | Organisation Communiste Libertaire | In French | → Political parties and movements |
| OCM | Organisation Civile et Militaire | In French | → Organizations and associations → History |
| OCM | Organisations Communes des Marchés | In French | → Organizations and associations → Economics |
| OCP | Office Chérifien des Phosphates = م ش ف | مجموعة المكتب الشريف للفوسفاط | In Arabic |
In French | → Mining → Chemical technology |
| OCQ | Ordre des Chimistes du Québec | In French | → Organizations and associations → Chemistry → Chemical technology |
| OCQ | Ordre des Chiropraticiens du Québec | In French | → Organizations and associations → Occult sciences |
| OCRB | Office Central pour la Répression du Banditisme | In French | → Police |
| OCRETH | Office Central pour la Répression de la Traite des Êtres Humains | In French | → Police → Slavery |
| OCRFM | Office Central pour la Répression du Faux Monnayage | In French | → Police |
| OCRGDF | Office Central pour la Répression de la Grande Délinquance Financière | In French | → Police → Finance |
| OCRTAEMS | Office Central pour la Répression du Trafic des Armes, des munitions, des produits Explosifs et des Matières Sensibles | In French | → Police → Military engineering |
| OCRTIS | Office Central pour la Répression du Trafic Illicite des Stupéfiants | In French | → Police |
| ODE | Observatoire du Devenir des Étudiants | In French | → Higher education, universities |
| ODE | Observatoire Départemental de l'Eau | In French | → Regional administration → Hydrology → Environmental technology, water supply, waste management |
| ODIT | Observation, Développement et Ingénierie Touristique | In French | → Tourism |
| OECE | Organisation Européenne de Coopération Économique = OEES | Organisasie vir Europese Ekonomiese Samewerking | In Afrikaans = ΟΕΟΣ | Οργανισμός Ευρωπαϊκής Οικονομικής Συνεργασίας | In Greek = OCEE | Organització per a la Cooperació Econòmica Europea | In Catalan = OEEC | Organisation for European Economic Co-operation | In English = OECE | Organizzazione Europea per la Cooperazione Economica | In Italian = OCEE | Organizaţia pentru Cooperare Economică Europeană | In Romanian = OECE | Organização para a Cooperação Económica Europeia | In Portuguese |
In French | → International relations → International economic cooperation |
| OEP | Observatoire Européen du Plurilinguisme | In French | → Organizations and associations → Language, linguistics, literature |
| OEST | Observatoire Économique et Statistique des Transports | In French | → Statistics → Economics → Transport and postal services |
| OF | Ordre de Fabrication | In French | → Maintenance and logistics |
| OFAJ | Office Franco-Allemand pour la Jeunesse | In French | → Organizations and associations → International relations |
| OFBSL | Observatoire de la Foresterie du Bas-Saint-Laurent | In French | → Environment, environmental sciences → Agricultural sciences |
| OFEFP | Office Fédéral de l'Environnement, des Forêts et du Paysage | In French | → Public administration, government → Nature → Forestry |
| OFP | Omnium Français des Pétroles | In French | → 665 |
| OFQJ | Office Franco-Québécois pour la Jeunesse | In French | |
| OFSPO | Office Fédéral du Sport = BASPO | Bundesamt für Sport | In German |
In French | → Central administration → Sport, physical exercises |
| OGAF | Opérations Groupées d'Aménagement du Foncier | In French | |
| OGE | Ordre des Géomètres Experts | In French | → Organizations and associations → Geodesy, cartography |
| OGM | Organisme Génétiquement Modifié | In French | → Biological sciences → Biotechnology |
| OGP | Organisation et Gestion de la Production | In French | → Management |
| OGS | Opération Grand Site | In French | |
| OI | Ordinateur Individuel | In French | → Serial publications, periodicals → Computer science |
| OIAC | Organisation pour l'Interdiction des Armes Chimiques (www.opcw.org) = OPWC | Organisation for the Prohibition of Chemical Weapons | In English |
In French | → Organizations and associations → International relations → Military engineering |
| OIBT | Organisation Internationale des Bois Tropicaux (www.itto.or.jp) = ITTO | International Tropical Timber Organization | In English = OIMT | Organización Internacional de las Maderas Tropicales | In Spanish |
In French | → Organizations and associations → Nature and society → Timber and woodworking industry |
| OICTS | Ordre International Chevaleresque de Tradition Solaire | In French | → Modern spiritual movements |
| OIE | Office International des Épizooties | In French | → Veterinary medicine |
| OIEau | Office International de l'Eau | In French | → Organizations and associations → Hydrology → Environmental technology, water supply, waste management |
| OIML | Organisation Internationale de Métrologie Légale | In French | → Organizations and associations → Standardization |
| OIN | Opération d'Intérêt National | In French | → Politics → Regional planning |
| OIP | Omnium International des Pétroles | In French | → 665 |
| OIPC | Organisation Internationale de Police Criminelle | In French | → International relations → Police |
| OIR | Organisation Internationale pour les Réfugiés = IRO | International Refugee Organization | In English |
In French | → United Nations → Migrations |
| OIT | Organisation Internationale du Travail = ILO | International Labour Organization | In English = ILO | Internacia Labor-Organizo | In Esperanto |
In French | → United Nations → Labour, labour economics |
| OIV | Organisation Internationale de la Vigne et du Vin | In French | → Organizations and associations → Agricultural sciences → Beverage industry |
| OJC | Organisation Juive de Combat | In French | → Organizations and associations → Judaism → History |
| OJD | Office de Justification de la Diffusion des Supports de Publicité | In French | → 6591 |
| OL | Olympique Lyonnais | In French | → Sport, physical exercises |
| OLAF | Office européen de Lutte Antifraude | In French | → Trade → Criminal law → Industrial property |
| OLP | Organisation de Libération de la Palestine = PLO | Palestine Liberation Organization | In English = FAT | Fələstin Azadlıq Təşkilatı | In Azerbaijani = ООП | Организация за освобождение на Палестина | In Bulgarian = OAP | Organització per a l'Alliberament de Palestina | In Catalan = OOP | Organizace pro osvobození Palestiny | In Czech = OLP | Organización para la Liberación de Palestina | In Spanish = PAE | Palestinaren Askapenerako Erakundea | In Basque = OLP | Organizaĵo por Liberigo de Palestino | In Esperanto = OLP | Organización para a Liberación da Palestina | In Galician = PLO | 팔레스타인 해방기구 | In Korean = OLP | Organização para a Libertação da Palestina | In Portuguese = OWP | Organizacja Wyzwolenia Palestyny | In Polish = PLO | パレスチナ解放機構 | In Japanese = ПЛО | Палестинската ослободителна организација | In Macedonian = PIO | Palestinos išsivadavimo organizacija | In Lithuanian = პგო | პალესტინის განთავისუფლების ორგანიზაცია | In Georgian = OLP | Organizzazione per la Liberazione della Palestina | In Italian = ООП | Организация освобождения Палестины | In Russian = ПЛО | Палестинска ослободилачка организација | In Serbian = PLO | 巴勒斯坦解放組織 | In Chinese = OВП | Організація визволення Палестини | In Ukrainian = FKÖ | Filistin Kurtuluş Örgütü | In Turkish |
In French | → Political parties and movements |
| OM | Olympique de Marseille | In French | → Sport, physical exercises |
| OMC | Organisation Mondiale du Commerce = MOK | Monda Organiz(aĵ)o pri Komerco | In Esperanto = MKO | Monda Komerca Organizaĵo | In Esperanto = WTO | World Trade Organization | In English |
In French | → International relations → Trade |
| OMD | Objectifs du Millénaire pour le Développement = MDG | Millennium Development Goals | In German = OSM | Obiettivi di Sviluppo del Millennio | In Italian = TPM | Tujuan Pembangunan Milenium | In Indonesian = ODM | Objetivos de Desarrollo del Milenio | In Spanish = MDM | Metas de Desenvolvimento do Milênio | In Portuguese |
In French | → United Nations → Development |
| OMI | Organisation Maritime Internationale = IMO | International Maritime Organization | In English = IMO | Internacia Mar-Organizo | In Esperanto |
In French | → International relations → Marine research, oceanography → 6295 → Agricultural sciences |
| OMM | Organisation Météorologique Mondiale = MMO | Monda Meteologia Organizo | In Esperanto = WMO | World Meteriological Organization | In English |
In French | → International relations → Meteorology, climatology |
| OMMI | Oblates Missionnaires de Marie Immaculée = OMMI | Oblate Missionaries of Mary Immaculate | In English = OMMI | Oblatas Misioneras de Maria Inmaculada | In Spanish = OMMI | Oblate Missionarie di Maria Immacolata | In Italian |
In French | → Roman catholic church |
| OMNSH | Observatoire des Mondes Numériques en Sciences Humaines (www.omnsh.org) | In French | → Organizations and associations → Computer science → Social sciences |
| OMPI | Organisation Mondiale de la Propriété Intellectuelle (www.wipo.int) = WIPO | World Intellectual Property Organisation | In English = MOIP | Monda Organizo pri Intelekta Proprieto | In Esperanto = WIPO | World Intellectual Property Organization | In English = OMPI | Organizaţia Mondială a Proprietăţii Intelectuale | In Romanian |
In French | → International relations → Industrial property → Artistic property |
| OMT | Organisation Mondiale du Tourisme = WTO | World Tourism Organization | In English = СТО | Светска туристичка организација | In Russian = OMT | Organização Mundial de Turismo | In Portuguese = OMT | Organizzazione Mondiale del Turismo | In Italian = OMT | Organización Mundial del Turismo | In Spanish = OMT | Organizazion Mondiâl dal Turisim | In Friulian |
In French | → United Nations → Tourism |
| OMT | Ordre Martiniste Traditionnel | In French | → Religion, theology → Occult sciences |
| ONBAH | Office National des Barrages et des Aménagements Hydro-agricoles | In French | → Central administration → 627 → Agricultural sciences |
| ONC | Organisme National de Certification | In French | → Standardization |
| ONC | Office National de la Chasse | In French | → Central administration → Fishing, hunting |
| ONCF | Office National des Chemins de Fer | In French | → Transport and postal services |
| OND | Observatoire National de la Délinquance | In French | → Sociology → Law, jurisprudence |
| ONE | Office National d’Électricité | In French | → Central administration → Electrical engineering |
| ONEP | Office National de l'Eau Potable | In French | → Organizations and associations → Environmental technology, water supply, waste management |
| ONERA | Office National d'Études et de Recherches Aéronautiques | In French | → Aeronautics, aircraft |
| ONERA | Office National d'Études et de Recherches Aérospatiales | In French | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| ONF | Office National des Forêts | In French | → Central administration → Forestry |
| ONG | Organisation Non Gouvernementale = ONGs | Organizações Não Governamentais | In Portuguese = NGO | Non-Governmental Organization | In English = NGO | Nichtregierungsorganisation | In German = ANG | Aozadur Nann-Gouarnamantel | In Breton = NRO | Ne-Registara Organizo | In Esperanto = ONG | Organizzazione non governativa | In Italian = LSM | Lembaga Swadaya Masyarakat | In Indonesian = ONG | Organización non gobernamental | In Galician = GKE | Gobernuz Kanpoko Erakunde | In Basque = ONG | Organización no gubernamental | In Spanish = ΜΚΟ | Μη κυβερνητικές οργανώσεις | In Greek = NNO | Nevládní nezisková organizace | In Czech = ONG | Organització no governamental | In Catalan = ННО | Неурядові неприбуткові організації | In Ukrainian = ONG | Organização não governamental | In Portuguese = NGO | Niet-gouvernementele organisatie | In Dutch = NVO | Nevyriausybinė organizacija | In Lithuanian |
In French | → Organizations and associations |
| ONH | Organisme National Habilité | In French |