Osa

Osa may refer to:

• Osa Peninsula, a peninsula in Costa Rica
• Osa, India, a village in Allahabad, India
• Osa, Warmian-Masurian Voivodeship (north Poland)
• Osa, Russia, name of several inhabited localities in Russia
• Osa class missile boat
• 9K33 Osa (SA-8 Gecko), a Soviet surface-to-air missile launcher
• M79 Osa, a Serbian/Yugoslav rocket launcher
• Avia B.122 Osa, a Czech trainer aircraft
• Osa (plant genus), a genus of plants in the Rubiaceae family
• Osa, nickname of former Takarazuka Revue actress Sumire Haruno

OSA as an acronym can stand for:

• Obstructive sleep apnea
• Office of the Science Advisor of the United States Environmental Protection Agency‎
• Office of Secret Actions, a fictional government department in Return to Castle Wolfenstein
• The Office of Special Affairs, a controversial department of the Church of Scientology
• Official Secrets Act
• Okefenokee Swamp Alliance, a conservation, protection and advocacy group
• Old Scona Academic High School, a school in Edmonton, Canada
• Old Stone Age (Paleolithic)
• Online Savings Account
• Online Sexual Activity
• Ontario Soccer Association
• Ontario Society of Artists
• Open Scripting Architecture for AppleScript
• Open Services Architecture
• Open skies agreement
• Open Solutions Alliance
• Open Spectrum Alliance
• Open Systems Adapter, an IBM Card for Mainframe
• Open systems architecture
• Operación San Andrés
• Operation Save America
• Opportunistic Spectrum Access (AKA Smart radio, see also related article Frequency-hopping spread spectrum)
• The Optical Society (OSA)
• Optical Spectrum Analyzer
• Optical Supply of Asia
• Order of Saint Anne
• Ordo Sancti Augustini (Order of Saint Augustine), the Roman Catholic Augustinian order
• Oregon Student Association
• Organizirana Skupnost Anarhistov (Organized Community of Anarchists), a Slovenian local/regional anarchist group.
• Organization of the Secret Army, French far-right nationalist group in Algeria who fought against its independence
• The old airport code for Osaka International Airport
• OSA Group, a Constructivist architectural association of the 1920s based in the USSR
• Oscilloquartz SA
• Oversampling
• Orissa Society of the Americas a non-profit organization that promotes understanding of Oriya culture and history
• OSA-OBA - Obavještajno sigurnosna / bezbjednosna agencija, an Intelligence and security agency of Bosnia and Herzegovina
• Oakland School for the Arts
• Osteosarcoma - medicine: oncology