Op art
Opa-locka, Florida
Opa-locka North, Florida
Opabinia
Opal
Opal, Wyoming
Opal Cliffs, California
Opaline
Opatija
Opava
Opcode
Opdyke West, Texas
OPEC
Opel
Opel Kadett
Opel Omega
Opel RAK.1 (plane)
Opelika, Alabama
Opelousas, Louisiana
Open (poker)
Open-access publishing
Open All Hours
Open architecture
Open Archives Initiative
Open Audio License
Open campaign
Open chain
Open circuit
Open class word
Open cluster
Open Cola
Open content
Open Content License
Open content movement
Open Content Project
Open Courseware
Open Data-Link Interface
Open Database Connectivity
Open Directory License
Open Directory Project
Open Document Interchange Format
Open-End Fund
Open field system
Open Fire
Open Firmware
Open formats
Open gaming
Open GIS Consortium
Open Government Information Awareness
Open Grid Services Architecture
Open hardware
Open Inventor
Open Law project
Open Letter to Hobbyists
OPEN LOOK
Open mail relay
Open map
Open mapping theorem
Open market
Open market purchases
Open marriage
Open Mind Common Sense
Open network architecture
Open patent
Open Publication License
Open publishing
Open Range (movie)
Open Root Server Confederation
Open sentence
Open set
Open shortest path first
Open Site
Open Skies Treaty
Open society
Open Society Institute
Open software
Open Software Foundation
Open Software License
Open sore
Open Sound System
Open source
Open Source Definition
Open Source Development Network
Open Source Initiative
Open-source intelligence
Open source intelligence
Open-source license
Open source movement
Open source record label
Open-sourcing
Open space
Open space conference
Open Space Meeting
Open spectrum
Open standard
Open System
Open system
Open system (system theory)
Open systems architecture
Open systems interconnect
Open Systems Interconnection Specification
Open Theism
Open Translation Engine
Open University
Open university
Open University of Hong Kong
Open-water diving
Open-wheeler
OpenACS
Openbox
OpenBSD
OpenDoc
OpenDOS
OpenDX
OpenEXR
OpenFacts
OpenFT
OpenGEM
OpenGL
OpenGL Performer
OpenGL plus plus
OpenHistory
Opening Address of the Second Vatican Council
Opening manual
Openlab
OpenLDAP
OpenMP
OpenMSX
OpenNAP
OpenOffice.org
OpenPGP
Openphoto.net
OpenRISC
OpenSound Control
OpenSSH
OpenStep
OpenTransport
OpenType
OpenZaurus
Opera
Opera (browser)
Opera Australia
Opera buffa
Opera game (chess)
Opera house
Opera metal
Opera seria
Operand
Operant conditioning
Operant conditioning chamber
Operating environment
Operating system
Operating system advocacy
Operating System Embedded
Operating systems timeline
Operating theatre
Operating time
Operation
Operation: Mindcrime
Operation Abercrombie
Operation Addition
Operation Adler
Operation Ajax
Operation Allied Force
Operation Alphabet
Operation Alsos
Operation Ambassador
Operation Amherst
Operation Anaconda
Operation Anadyr
Operation Anklet
Operation Any Soldier
Operation Apollo
Operation Archery
Operation Archway
Operation Argus
Operation Ariel
Operation Artur
Operation Assaf
Operation Attila
Operation Avalanche
Operation Avalanche (Afghanistan)
Operation Avalanche (child pornography)
Operation Avalanche (World War II)
Operation Baobab
Operation Barbarossa
Operation Barclay
Operation Basalt
Operation Begonia
Operation Bernhard
Operation Big
Operation Biting
Operation Black Buck
Operation Blau
Operation Blessing International
Operation Boardman
Operation Bodyguard
Operation Bojinka
Operation Bowline
Operation Bramble Bush
Operation Bulldog Mammoth
Operation Canbelow
Operation Candytuft
Operation Canuck
Operation Catchpole
Operation Champion
Operation Chariot
Operation Chestnut
Operation Chettyford
Operation Chicago
Operation Chromite
Operation Clambake
Operation Claret
Operation Clawhammer
Operation Claymore
Operation Coast
Operation Cold Comfort
Operation Colossus
Operation Compass
Operation Condor
Operation Cooney
Operation Corkscrew
Operation Coronet
Operation Corporate
Operation Crossroads
Operation Crosstie
Operation Cycle
Operation Danny
Operation Deadlight
Operation Defensive Shield
Operation Defoe
Operation Dekel
Operation Desert Farewell
Operation Desert Fox
Operation Desert Scorpion
Operation Detachment
Operation Detroit
Operation Dingson
Operation Dominic I and II
Operation Donnerschlag
Operation Dove
Operation Downfall
Operation Downwood
Operation Dragoon
Operation Driftwood
Operation Drumbeat
Operation Dunhill
Operation Dynamo
Operation Eagle Claw
Operation Echo
Operation El Dorado Canyon
Operation Elmira
Operation Emery
Operation Entebbe
Operation Epsom
Operation Falcon
Operation Felix
Operation Ferdinand
Operation Flashpoint
Operation Flavius
Operation Flintlock
Operation Fortitude
Operation Foxley
Operation Frankton
Operation Fustian
Operation Gaff
Operation Gambit
Operation Gauntlet
Operation Gold
Operation Golden Pheasant
Operation Gomorrah
Operation Goodwood
Operation Granby
Operation Greif
Operation Grün
Operation Gruen
Operation Guardian
Operation Gunnerside
Operation Hailstorm
Operation Harborage
Operation Haven Denial
Operation Headstrong
Operation Herbstnebel
Operation Herbstreise
Operation Hiram
Operation Husky
Operation Iron Hammer
Operation Ivory Coast
Operation Ivy
Operation Ivy Blizzard
Operation Ivy Cyclone II
Operation Jael
Operation Just Cause
Operation Kedem
Operation Keelhaul
Operation Keyhole
Operation Keystone
Operation Kilshon
Operation Kinetic
Operation Kremlin
Operation Ladbroke
Operation Latchkey
Operation Lost
Operation Loyton
Operation Magic Carpet
Operation Majestic
Operation Mandrel
Operation Maple
Operation Market Garden
Operation Mars
Operation Megaphone
Operation Mindfuck
Operation Mongoose
Operation Mountain Viper
Operation Musketeer
Operation Nachshon
Operation Narcissus
Operation Nelson
Operation Neptune
Operation Newton
Operation Niblick
Operation Nimrod
Operation Noah
Operation Northwoods
Operation Nougat
Operation Olympic
Operation Ore
Operation Paperclip
Operation Pastel
Operation Peace for Galilee
Operation Peace for the Galilee
Operation Pedro Pan
Operation Pegasus
Operation Peter Pan
Operation Pin
Operation Plowshare
Operation Pomegranate
Operation Provide Comfort
Operation Purple Warrior
Operation Quicksilver
Operation Ranch Hand
Operation Red Dawn
Operation Reinhard
Operation Rifles Blitz
Operation Rolling Thunder
Operation Rosario
Operation Rot
Operation Samwest
Operation Savannah
Operation Scavenger
Operation Schfifon
Operation Sealion
Operation Sharp Edge
Operation Shingle
Operation Shining Express
Operation Shylock
Operation Silver
Operation Skye
Operation Sledgehammer
Operation Slipper
Operation Sonneblume
Operation Span
Operation Stardust
Operation Storax
Operation Storfang
Operation Storm
Operation Support
Operation Sutton
Operation Suzannah
Operation Tailwind
Operation Tannenberg
Operation Telic
Operation Telic order of battle
Operation Tinderbox
Operation TIPS
Operation Tombola
Operation Tonga
Operation Torch
Operation Totalize
Operation Uranus
Operation Urgent Fury
Operation Valiant Strike
Operation Veritas
Operation Wahrung
Operation Warrior Sweep
Operation Weserübung
Operation Whetstone
Operation Yoav
Operational amplifier
Operational art
Operational definition
Operational semantics
Operational service period
Operations
Operations research
Operator
Operator (physics)
Operator assistance
Operator logo
Operator norm
Operator overloading
Operetta
Operon
Opeth
Opglabbeek
Opheim, Montana
Ophel
Ophelia
Ophelia (character)
Ophelia (moon)
Ophicleide
Ophidiiformes
Ophidiocephalus
Ophiocoma wendtii
Ophiodes
Ophioglossoid
Ophiognomon
Ophiolites
Ophiomorus
Ophion
Ophioscincus
Ophir
Ophir, Colorado
Ophir, Utah
Ophisaurus
Ophisops
Ophites
Ophiuchus
Ophiussa
Ophrah
Ophrys
Ophrys lutea
Ophthalmology
Ophthalmoscope
Opiate
Opiate (album)
Opiliones
Opinion poll
Opioid analgesic
Opipeuter
Opium
Opium of the people
Opium Wars
Opluridae
Oplurus
Opmeer
Opochtli
Opoczno
Opodeldoc
Opole
Opole Voivodship
Oporto
Opossum
Opp, Alabama
Oppdal
Oppegċrd
Oppelo, Arkansas
Oppenheim, New York
Oppland
Opportunity, Washington
Opportunity cost
Opposed piston
Opposite lock
Opposition
Opposition leader
Oprah
Oprah Winfrey
Oprichina
Ops
Opsterland
Optatam Totius
Opteron
Optic chiasm
Optic nerve
Optic neuritis
Optical abberation
Optical amplifier
Optical astronomy
Optical attenuator
Optical axis
Optical brightener
Optical character recognition
Optical communication
Optical computer
Optical density
Optical depth
Optical disc
Optical effect
Optical engineering
Optical fiber
Optical illusion
Optical isolator
Optical isomerism
Optical microscope
Optical path length
Optical phenomena
Optical phenomenon
Optical power budget
Optical power margin
Optical rotation
Optical Society of America
Optical spectrum
Optical switch
Optical telegraph
Optical telescope
Optical time domain reflectometer
Optical tweezers
Optical waveguide
Optical window
Optics
Optima
Optima, Oklahoma
OPTIMAES
Optimal control
Optimal solutions for Rubik's Cube
Optimal-substructure
Optimality Theory
Optimism
Optimist
Optimist International
Optimistic concurrency control
Optimization
Optimization (computer science)
Optimization (mathematics)
Optimization of Java
Optimus Prime
Option
Option style
Option time value
Optoelectronic
Optoelectronics
Optometry
Optus
Opuntia
Opus
Opus Dei
Opus number
Opus the penguin
Opwijk