Osa
Osa may refer to:
- Osa peninsula, a peninsula in Costa Rica
- Osa, Allahabad, 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
- 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