• Allied Pilots Association, the certified collective bargaining agent for American Airlines pilots
• American Philological Association, North American scholarly organization devoted to Greek and Roman civilization
• American Philosophical Association, main professional organization for philosophers in the United States
• American Planning Association, a professional organization representing the field of city and regional planning in the United States
• American Polygraph Association
• American Poolplayers Association
• American Poultry Association
• American Protective Association, an American anti-Catholic organization during the Gilded Age
• American Psychiatric Association
• American Psychological Association; also
  • APA style, writing format developed by the above
• American Psychoanalytic Association
• American Psychopathological Association
• APA – The Engineered Wood Association, formerly known as the American Plywood Association

• Azəri-Press Agentliyi
• Austria Presse Agentur
• Administrative Procedure Act
• Advanced Pricing Agreement
• Adelsprüfungsaussschuss der DAG bis 1945 (adelsrechtlicher Fachbegriff), Adelsprüfung, Adelsrecht VdDA
• Airport Promotion Agencies
• American Payroll Association
• Amateur Press Association
• American Philological Association
• American Philosophical Association
• American Planning Association
• American Plywood Association
• American Poolplayers Association
• American Psychiatric Association
• American Psychological Association
• American Psychopathological Association
• Amerindian People's Association of Guyana
• Antagonist Perpetrated Aggression, eine Kampfkunst
• Apache Railway
• Archivierte Patienten Akte
• Asien-Pazifik-Ausschuss der Deutschen Wirtschaft
• Außenpolitisches Amt der NSDAP
• Australian Physiotherapy Association
• Australian Progressive Alliance
• Acolytes Protection Agency
• Flughafen Centennial im US-amerikanischen Bundesstaat Colorado als IATA-Code

1. OMDIRIGERINGApa

• En vardaglig benämning på primater
• Apa, ett av de tolv zodiakdjuren inom Kinesisk astrologi
• Apa, mesanstagseglet eller ett (gaffel)segel på samma plats på den framförvarande masten (vanligen stor- eller kryssmasten).
• American Psychiatric Association, det amerikanska psykiatrikerförbundet
• American Pulling Alliance, en amerikansk weight pulling-organisation
• American Psychological Association, det amerikanska psykologförbundet
  • APA style, ett vanligt använt format för forskningsartiklar inom samhälls- och beteendevetenskap med ursprung i American Psychological Association och dess tidskrifter.
• En förkortning för American Pale Ale, en typ av amerikansk ale.

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