(Main list of acronyms)

__NOTOC__

  • O – (i) Oberst – Observer – Obstacle – Octal – Officer – Official – Oh – Operational – Operator – Oprah (magazine) – Outstanding – (s) Oxygen

OA

  • OA – (i) Operational Analysis – (i) Overeaters Anonymous
  • OAC – (i) On Approved Credit
  • OAP – Old Age Pensioner (UK)
  • OAS – (i) Organization of American States
  • OARSI – (i) Osteoarthritis Research Society International
  • OASIS – (a) Objects and Agents for Information Systems and Simulation – Organization for the Advancement of Structured Information Standards
  • OASIS – (a) Ontario Agencies Supporting Individuals with Special Needs
  • OASIS – (a) Ontario Association of Sewage Industry Services
  • OASP – (i) Operational Analysis Support Paper/Plan
  • OAU – (i) Organization of African Unity

OB

  • ob – (p) obiit (Latin, "(s) he died")
  • OB
  • (p) Obedience
  • Obligation
  • Obligatory
  • Obsolete
  • Obstetrics
  • (i) Ocean Beach (California)
  • Off Break (cricket)
  • Old Bryanstonian
  • Order of Battle
  • Out-of-Bounds (golf)
  • Outlet Box (electrical)
  • (p) Overbought (stock market)
  • (i) Oversight Board
  • OBE – (i) Officer of the Order of the British Empire
  • OBJ
  • (p) Objective (military parlance)
  • (i) Odell Beckham Jr. (American football wide receiver)
  • OBM – (p) Obsidian Black Metallic (automobile paint color)
  • OBOR – (i) One Belt One Road, a former name of the China-sponsored Belt and Road Initiative
  • OBS
  • (p) Observation/Observer
  • Obsolete
  • Obstacle
  • (i) Off Balance Sheet
  • Optical Burst Switching (IEEE)
  • Organic Brain Syndrome
  • Organization(al) Breakdown Structure
  • OBSS
  • (i) Off Board Sensor Systems
  • Ordo Byantinus Sancti Sepulchri (Byzantine Order of the Holy Sepulchre)
  • Orbiter Boom Sensor System (space shuttle)
  • Origins Billion Star Survey
  • OBX – (p) Outer Banks (North Carolina)

OC

  • oc – (s) Occitan language (ISO 639-1 code)
  • OC – (i) Officer Commanding
  • OCA – (i) Observatoire de la Côte d'Azur – Offensive Counter-Air
  • OCD – (i) Obsessive-Compulsive Disorder
  • OCFS – (i) Oracle Cluster File System
  • OCFS [http://ocfs.ny.gov/main/] – (i) Office of Children & Family Services
  • OCFS2 – (i) Oracle Cluster File System Release 2
  • oci – (s) Occitan language (ISO 639-2 code)
  • OCIDS – (i) Optical Combat Identification System
  • OCMCC – (i) [http://www.OrchardCountyMcc.co.uk] Orchard County MCC
  • OCONUS - Outside Continental United States
  • OCN – (i) Oncology Certified Nurse
  • OCO – (i) Oort Cloud Object
  • OCOKA – (a) Observation, Cover and concealment, Obstacles, Key terrain, and Avenues of approach (mnemonic)
  • OCR – (i) Optical Character Recognition
  • OCS – see entry

OD

  • OD
  • (i) Old Dragon
  • Ordnance Datum (nautical charts)
  • (p) Overdose
  • ODAS – (a) OCA-DLR Asteroid Survey
  • ODB
  • (i) Ol' Dirty Bastard (rapper)
  • (i) One Dirty B*tch/Broad/Babe (professional wrestler)
  • (i) Operational Data Base
  • (i) Original David Baker (professional poker player; used to distinguish from another professional poker player of the same name)
  • (i) Oxford Dictionary of Byzantium
  • ODBC – (i) Open DataBase Connectivity
  • ODI
  • (i) Office for Disability Issues (UK government agency)
  • One Day International (cricket)
  • Open Data-Link Interface
  • Oracle Data Integrator

OE

  • OEA – (i) (U.S.) Office of Economic Adjustment
  • OED – (i) Oxford English Dictionary
  • OECD – (i) Organisation for Economic Co-operation and Development (international)
  • OEG – (i) Operation Exposure Guidance
  • OEIS - (i) On-Line Encyclopedia of Integer Sequences
  • OEM – (i) Original equipment manufacturer

OF

  • OFA – (i) Occipital Face Area
  • OFDA – (i) U.S. Agency for International Development's Office of Foreign Disaster Assistance

OG

  • OG:
  • Objective Glass, see Objective (optics)
  • Obstetrics and gynaecology
  • Offensive Guard, see Guard (American football)
  • Old Giggleswickian, a former pupil of Giggleswick School
  • Old Gower, a former pupil of University College School
  • Old Gregorian, a former pupil of Downside School
  • Old Greshamian, a former pupil of Gresham's School
  • Old Gold, a dark yellow
  • Olympic Games
  • Original Gangster, see Gangster
  • Original Gravity, see Gravity (beer)
  • Outpost Gallifrey, a Doctor Who fansite.
  • Own goal, in soccer, a goal scored by a player in their own side's goal
  • OG: Optimized Gaia, theory the earth optimizes itself to promote life, and popular movement to Promote Human Progress in Harmony with the Natural World.
  • OG: Original Gangster, an album by Ice-T
  • OGC – (i) Open Geospatial Consortium
  • OGD – (i) Other Government Department
  • OGO – (i) Other Government Organization
  • OGX – OUARGLA – a petroleum state in the south of Algeria

OH

  • OH – (s) Ohio (postal symbol)
  • OHC – (i) OverHead-Cam engine
  • OHHLA – (a) Original Hip-Hop Lyrics Archive
  • OHIP – (a) Ontario Health Insurance Plan
  • OHMS – (i) On His (or Her Majesty's Service) (also written: O.H.M.S.)
  • OHP – (i) Observatoire de Haute-Provence
  • OHSS – (p) Ovarian Hyperstimulation Syndrome

OI

  • OIC – (i) Officer In Charge
  • OIE – (i) World Organisation for Animal Health (originally the Office international des épizooties, French for "International Epizootic Office")
  • OIF – (i) Operation Iraqi Freedom
  • OIOC – (i) Oriental & India Office Collections (in the British Library)

OJ

  • oj – (s) Anishinaabe language (Ojibwa) (ISO 639-1 code)
  • OJ – (i) Orange Juice – O. J. Simpson
  • oji – (s) Anishinaabe language (Ojibwa) (ISO 639-2 code)
  • OJT – On-the-Job Training

OK

  • OK
  • (s) Oklahoma (postal symbol)
  • (i) oll korrect (facetious alteration of "all correct", 1839)
  • OKC – (a) Oklahoma City

OL

  • OLED – (a) Organic Light-Emitting Diode
  • OLS – (i) Operational Linescan System

OM

  • om – (s) Oromo language (ISO 639-1 code)
  • OM – (s) Oman (ISO 3166 digram) – Olympique de Marseille (French football club)
  • OMA – (i) Open Mobile Alliance – Operations & Maintenance, Army
  • OMB – (i) U.S. Office of Management and Budget – Ontario Municipal Board – (i) Order of Mapungubwe in Bronze
  • OMD – (i) Orchestral Manoeuvres in the Dark (1980s pop group)
  • OME – (i) Osaka Mercantile Exchange
  • OMFG – (i) Oh My F**king God
  • OMG – (i) Oh My God or Or My Gosh
  • OMGW – (i) "Oh My Gosh it's Windy"
  • OMN – (s) Oman (ISO 3166 trigram)
  • OMNCS – (i) U.S. Office of the Manager for the National Communications System
  • OMP – (i) Order of Mapungubwe in Platinum
  • OMR – (s) Omani rial (ISO 4217 currency code)
  • OMS – (i) Order of Mapungubwe in Silver
  • OMT – (i) Object Model Template
  • OMW – (i) On My Way, Oh My Word

ON

  • ON – (s) Ontario (postal symbol)
  • Onna – Oniong, Nnung Ndem, and Awa, a Local Government Area in Nigeria
  • ONC – (i) Orthopaedic Nurse Certified
  • ONCE – (a) Organización Nacional de Ciegos Españoles (Spanish, "National Organization for the Spanish Blind")
  • ONÉRA – (a) Office national d'études et de recherches aérospatiales (French, "Aeronautics and Space Research Center")
  • ONG – (i) Orthodontic National Group
  • ONH – (i) Óglaigh na hÉireann (Irish idiom for "soldiers of Ireland"), used for the following:
  1. Historically, as the Irish-language name for the original Irish Republican Army ("Old IRA")
  2. In modern times, as the Irish-language name of the Defence Forces of Ireland
  3. The name of two groups claiming descent from the Old IRA, one a currently inactive splinter group of the Continuity IRA and the other an active splinter group of the Real IRA
  • ONI – (i) (U.S.) Office of Naval Intelligence
  • ONS – (i) Operational Needs Statement

OO

  • OO – (i) Object Oriented – Over & Out
  • OOO – (i) Out Of the Office
  • OOAD – (i) Object-Oriented Analysis and Design
  • OOBE – (a) Out-of-body experience
  • OOCL – (i) Orient Overseas Container Line
  • OODA – (i) Observation, Orientation, Decision, Action loop (a.k.a. Boyd's Loop)
  • OOMF – (i) One Of My Followers
  • OOP – (i) Object-Oriented Programming – Out Of Print
  • OOS – (i) Occupational Overuse Syndrome – OneSAF Objective System – Open Operating System – Out Of Service
  • OOTW – (i) (Military) Operations Other Than War (MOOTW or OOTW)

OP

  • OP
  • (i) Observation Point/Post
  • Ocean Pacific (surfwear and swimwear brand)
  • Original Poster (internet)
  • Order Point, in inventory management; the inventory state at which more items should be ordered. Often expressed as a part of OP/OQ (when quantity OP is reached, order OQ new items)
  • Overpowered, often used to refer to fictional characters (e.g. Superman) or game mechanics (e.g. the Black Lotus in Magic: the Gathering) that are considered disproportionately strong
  • OPA – (i) Other Procurement, Army
  • OPAC – (a) Online Public Access Catalogue
  • op cit – (p) opera citata (Latin, "in the work cited")
  • OPCON – (p) Operational control
  • OPCW – (i) Organisation for the Prohibition of Chemical Weapons
  • OPEC – (a) Organization of the Petroleum Exporting Countries
  • OpenStreetMap - (p) OpenStreetMap
  • OPFOR – (p) Opposing force(s)
  • OPI
  • (i) Office of Primary Interest
  • Open Prepress Interface
  • OPINTEL – (p) Operational Intelligence
  • OPLAN – (p) Operation plan (also OpPlan)
  • OPORD – (p) Operation order
  • OPP
  • (i) Ontario Provincial Police
  • Operational Planning Process
  • Other People's Property/Pussy/Penis (song)
  • OPS
  • (i) On-base plus slugging (baseball statistics)
  • (p) Operations
  • OPSEC
  • (p) Operations security
  • Open Platform for Security
  • OPSI
  • (a) Overwhelming post splenectomy infection
  • UK Office of Public Sector Information
  • OPTAR – (p) Operational target
  • OPV – (i) Offshore Patrol Vessel

OQ

  • OQ - (i) Order Quantity, in inventory management; the quantity of new items to be ordered. Often expressed as a part of OP/OQ (when quantity OP is reached, order OQ new items)

OR

  • or – (s) Oriya language (ISO 639-1 code)
  • OR – (i) Operating Room (surgery) – Operational/Operations Research – (s) Oregon (postal symbol) - overreciprocation - when the leader of an inner circle friendship contacts a friend more than is wanted or reasonable
  • ORAU – (a/i) Oak Ridge Associated Universities
  • ORB – (a/i) Object Request Broker
  • ORBAT – (p) Order of Battle
  • ORD – (i) O'Hare International Airport in Chicago, Illinois (IATA Airport Code ORD)
  • ORD – (i) Office of Research and Development – Operational Requirements Document
  • ORF – (i) Operational Readiness Float
  • ori – (s) Oriya language (ISO 639-2 code)
  • ORISE – (a) Oak Ridge Institute for Science and Education
  • orm – (s) Oromo language (ISO 639-2 code)
  • ORNL – (i) Oak Ridge National Laboratory
  • ORR – (i) Oak Ridge Reservation (U.S. DOE) – Office of Rail Regulation (UK government) – Office of Refugee Resettlement – (CIA) Office of Research and Reports – Operational Readiness Rate – Operational Readiness Review
  • ORSA – Oxacillin-resistant Staphylococcus aureus – Operations Research Society of America

OS

  • OS – (s) Operating system
  • os – (s) Ossetic language (ISO 639-1 code)
  • Os – (s) Osmium
  • OSA – (i) Order of St. Augustine
  • OSCE – (i) Organization for Security and Co-operation in Europe
  • OSD – (i) U.S. Office of the Secretary of Defense – (i) On-screen Display
  • OSDL – (i) Open Source Development Labs
  • OSE – (a) Own Separate Entrance
  • OSERS – (a) U.S. Department of Education Office of Special Education and Rehabilitative Services
  • OSETI – (a) Optical SETI also Optical SETI
  • OSGeo - (a) Open Source Geospatial Foundation (OSGeo)
  • OSHA – (a) Occupational Safety and Health Administration
  • OSI – (i) Office of Strategic Influence – Ontario Swine Improvement – Open Source Initiative – Open Systems Interconnection
  • OSIA – (i) (U.S.) On-Site Inspection Agency
  • OSL – (i) Open Source License – Optically Stimulated Luminescence – Orbiting Solar Laboratory
  • OSIRIS
  • (a) Optical, Spectroscopic, and Infrared Remote Imaging System (astronomical system on the Rosetta spacecraft)
  • Optical System for Imaging and low Resolution Integrated Spectroscopy (astronomical system on the land-based Gran Telescopio Canarias)
  • OSM – (i) One Saturday Morning
  • OSMF - (a) OpenStreetMap Foundation
  • OSPA – (a) Operations Security Professional's Association site of OSPA
  • OSPA – (i) Oregon School Psychologists Association [http://www.ospaonline.com]
  • OSRH – (i) Oružane Snage Republike Hrvatske (en: Armed forces of the Republic of Croatia)
  • oss – (s) Ossetic language (ISO 639-2 code)
  • OSS – (i) Office of Strategic Services (1942–1945, forerunner of CIA)
  • OSU – (i) Ohio State University – Oklahoma State University

OT

  • OTA – Occupational Therapy Assistant, (i) Office of Technology Assessment – (a/i) Orthodontic Technicians Association
  • OTAC – (i) Orthodontic Technicians Association Conference – (i) Orthodontic Technicians Association Council
  • OTB – (i) Off The Ball – (i) Offtrack Betting – (p) OneSAF Testbed (a descendant of ModSAF)
  • OTC – (i) Over-The-Counter (drugs)
  • OTD – (i) Off the derech (referring to an Orthodox Jew who has stopped practicing the tenets of his or her faith)
  • OTEA – (i) (U.S. Army) Operational Test Evaluation Agency
  • OTI – (i) Office of Transition Initiatives (United States Agency for International Development)
  • OTK One Turn Kill
  • OTO – (i) Ordo Templi Orientis (Latin, "Order of the Temple of the East", i.e. the Order of Oriental Templars)
  • OTOH – (i) On The Other Hand
  • OTS – Off the scale, sexually untouchable except for a lot of money.
  • OTSBH – (i) Over The Shoulder Boulder Holder
  • OTW – (i) On The Way
  • OTYBL – (i) Over To You Blue Leader
  • OTYRL – (i) Over To You Red Leader

OU

  • OU – (p) University of Oklahoma

OV

  • OVC
  • (s) Overcast (METAR Code)
  • (i) Ohio Valley Conference
  • OVV – (i) Optically Visually Violent, or Optically Violently Variable – a type of quasar

OW

  • OW – (i) Old Wykehamist
  • OWN – (i) Oprah Winfrey Network

OX

  • OX – (p) IATA code for Orient Thai Airlines
  • OXC – (p) Optical cross-connect
  • OXF – (p) IATA code for London Oxford Airport
  • Oxfam – (p) Oxford Committee for Famine Relief (international poverty relief organization)
  • OXM – (i) Official Xbox Magazine
  • OXR – (p) IATA code for Oxnard Airport
  • OXT – (s) Oxytocin

OY

  • Oy – (p) Osakeyhtiö (Finnish, "stock company")
  • Oyj – (p) Julkinen osakeyhtiö (Finnish, "public stock company")

OZ

  • OZ – Ounce