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Glossary · Nouns · O

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TermTypeDefinitionClassificationsUpdated
Operating System FingerprintingnounMWEAnalyzing characteristics of packets sent by a target, such as packet headers or listening ports, to identify the operating system in use on the target.SystemMay 9, 2026
Operating TablenounMWEtable on which the patient lies during a surgical operationverifiedMay 18, 2026
Operating TheaternounMWEa room in a hospital equipped for the performance of surgical operationsverifiedMay 18, 2026
Operating TheatrenounMWEa room in a hospital equipped for the performance of surgical operationsverifiedMay 18, 2026
operationnounAn organized activity involving multiple people.ProcessMay 9, 2026
Operation CodenounMWEthe portion of a set of operation descriptions that specifies the operation to be performedverifiedMay 18, 2026
Operational CasualtynounMWEloss of military equipment in field operationsverifiedMay 18, 2026
Operational CellnounMWEa terrorist cell that performs clandestine activitiesverifiedMay 18, 2026
operational controlnounMWEThe day-to-day security procedures and mechanisms to protect operational systems. The operational controls consist of the physical, environmental and personnel security controls. These controls deal with the everyday operation of a company or organization to ensure all objectives are achieved.ControlRegulatedMay 9, 2026
Operational DamagenounMWEloss of military equipment in field operationsverifiedMay 18, 2026
operational exercisnounMWEAn action-based exercise where personnel rehearse reactions to an incident scenario, drawing on their understanding of plans and procedures, roles, and responsibilities.ProcessMay 9, 2026
operational exercisenounMWEAn action-based exercise where personnel rehearse reactions to an incident scenario, drawing on their understanding of plans and procedures, roles, and responsibilities.ProcessMay 12, 2026
Operational IT plannounMWETypically, the plans that are made by front-line, or low-level, IT managers. Operational IT plans are focused on the specific procedures and processes that implement the larger strategic plan.ProcessMay 9, 2026
Operational KeynounMWEKey intended for use over-the-air for protection of operational information or for the production or secure electrical transmission of key streams.CredentialRegulatedCUIMay 9, 2026
operational performance reportnounMWEA report that details the findings of a performance review of a business's operations.ArtifactInternalMay 12, 2026
operational resiliencenounMWEThe ability of an FMI to: (i) maintain essential operational capabilities under adverse conditions or stress, even if in a degraded or debilitated state; and (ii) recover to effective operational capability in a time frame consistent with the provision of critical economic services.CapabilityRegulatedMay 9, 2026
Operational risknounMWEThe risk of failure or loss resulting from inadequate or failed processes, people, or systems.ThreatRegulatedMay 12, 2026
Operational Vulnerability InformationnounMWEInformation that describes the presence of an information vulnerability within a specific operational setting or network.VulnerabilityRegulatedCUIMay 12, 2026
Operational WaivernounMWEAuthority for continued use of unmodified COMSEC end-items pending the completion of a mandatory modification.RequirementRegulatedCUIMay 9, 2026
Operationalismnounthe doctrine that the meaning of a proposition consists of the operations involved in proving or applying itverifiedMay 18, 2026
OperationalizationnounProcessMay 14, 2026
Operations CodenounMWECode composed largely of words and phrases suitable for general communications use.ArtifactRegulatedCUIMay 9, 2026
Operations ResearchnounMWEresearch designed to determine most efficient way to do somethingverifiedMay 18, 2026
Operations SecuritynounMWESystematic and proven process by which potential adversaries can be denied information about capabilities and intentions by identifying, controlling, and protecting generally unclassified evidence of the planning and execution of sensitive activities. The process involves five steps: identification of critical information, analysis of threats, analysis of vulnerabilities, assessment of risks, and application of appropriate countermeasures.ProcessRegulatedCUIMay 9, 2026
Operations TechnologynounMWEThe hardware and software systems used to operate industrial control devices.SystemRegulatedMay 9, 2026
Operative FieldnounMWEthe area that is open during surgeryverifiedMay 18, 2026
OperatornounA role assumed by the person performing remote control or teleoperation, semi-autonomous operations, or other human-in-the-loop types of operationsRoleMay 18, 2026
Operator GenenounMWEa gene that activates the production of messenger RNA by adjacent structural genesverifiedMay 18, 2026
Operculumnouna hard flap serving as a cover for (a) the gill slits in fishes or (b) the opening of the shell in certain gastropods when the body is retractedverifiedMay 18, 2026
Operettanouna short amusing operaverifiedMay 18, 2026
Operonnouna segment of DNA containing adjacent genes including structural genes and an operator gene and a regulatory geneverifiedMay 18, 2026
Operosenessnounthe quality of requiring extended effortverifiedMay 18, 2026
Ophidiannounlimbless scaly elongate reptileverifiedMay 18, 2026
Ophidismnounpoisoning by snake venomverifiedMay 18, 2026
Ophiolatrynounthe worship of snakesverifiedMay 18, 2026
Ophryonnounthe craniometric point in the midline of the forehead immediately above the orbitsverifiedMay 18, 2026
Ophthalmectomynounsurgical removal of an eyeverifiedMay 18, 2026
Ophthalmianounsevere conjunctivitisverifiedMay 18, 2026
Ophthalmia NeonatorumnounMWEophthalmia in newbornsverifiedMay 18, 2026
Ophthalmic ArterynounMWEa branch of the internal carotid artery that supplies the eye and neighboring structuresverifiedMay 18, 2026
Ophthalmic VeinnounMWEeither of two veins that serve the eyeverifiedMay 18, 2026
Ophthalmitisnounsevere conjunctivitisverifiedMay 18, 2026
Ophthalmologistnouna medical doctor specializing in the diagnosis and treatment of diseases of the eyeverifiedMay 18, 2026
Ophthalmologynounthe branch of medicine concerned with the eye and its diseasesverifiedMay 18, 2026
Ophthalmoplegianounparalysis of the motor nerves of the eyeverifiedMay 18, 2026
Ophthalmoscopenounmedical instrument for examining the retina of the eyeverifiedMay 18, 2026
Ophthalmoscopynounexamination of the interior of an eye using an ophthalmoscopeverifiedMay 18, 2026
Opiatenouna narcotic drug that contains opium or an opium derivativeverifiedMay 18, 2026
Opinion PollnounMWEan inquiry into public opinion conducted by interviewing a random sample of peopleverifiedMay 18, 2026
Opisthorchiasisnouninfestation with flukes obtained from eating raw fishverifiedMay 18, 2026
Opisthotonosnounsevere spasm in which the back arches and the head bends back and heels flex toward the backverifiedMay 18, 2026
Opiumnounan addictive narcotic extracted from seed capsules of the opium poppyverifiedMay 18, 2026
Opium AddictnounMWEsomeone addicted to opiumverifiedMay 18, 2026
Opium DennounMWEa building where opium is sold and usedverifiedMay 18, 2026
Opium PoppynounMWEsouthwestern Asian herb with greyish leaves and white or reddish flowersverifiedMay 18, 2026
Opium TakernounMWEsomeone addicted to opiumverifiedMay 18, 2026
Opopanaxnounan odorous gum resin formerly used in medicinesverifiedMay 18, 2026
Opossumnounnocturnal arboreal marsupial having a naked prehensile tail found from southern North America to northern South AmericaverifiedMay 18, 2026
Opossum RatnounMWEterrestrial marsupials of southern South America that resemble shrewsverifiedMay 18, 2026
Opossum ShrimpnounMWEshrimp-like crustaceans whose females carry eggs and young in a pouch between the legsverifiedMay 18, 2026
Opossum WoodnounMWEmedium-sized tree of West Virginia to Florida and TexasverifiedMay 18, 2026
Opportunenessnountimely convenienceverifiedMay 18, 2026
Opportunismnountaking advantage of opportunities without regard for the consequences for othersverifiedMay 18, 2026
Opportunistic InfectionnounMWEany infection caused by a microorganism that does not normally cause disease in humansverifiedMay 18, 2026
Opportunitynouna possibility due to a favorable combination of circumstancesverifiedMay 18, 2026
Opportunity CostnounMWEcost in terms of foregoing alternativesverifiedMay 18, 2026
Opposernounsomeone who offers oppositionverifiedMay 18, 2026
Opposite NumbernounMWEa person or thing having the same function or characteristics as anotherverifiedMay 18, 2026
Opposite WordnounMWEa word that expresses a meaning opposed to the meaning of another word, in which case the two words are antonyms of each otherverifiedMay 18, 2026
Oppositenessnounthe relation between opposed entitiesverifiedMay 18, 2026
Oppositionnounan armed adversary (especially a member of an opposing military force)verifiedMay 18, 2026
Oppressionnounthe state of being kept down by unjust use of force or authority: 'after years of oppression they finally revolted'verifiedMay 18, 2026
Oppressivenessnoununwelcome burdensome difficultyverifiedMay 18, 2026
Oppressornouna person of authority who subjects others to undue pressuresverifiedMay 18, 2026
Opprobriumnounstate of disgrace resulting from public abuseverifiedMay 18, 2026
Opsinnounretinal protein formed by the action of light on rhodopsinverifiedMay 18, 2026
Opsoninnounan antibody in blood serum that attaches to invading microorganisms and other antigens to make them more susceptible to the action of phagocytesverifiedMay 18, 2026
Opsonisationnounprocess whereby opsonins make an invading microorganism more susceptible to phagocytosisverifiedMay 18, 2026
Opsonizationnounprocess whereby opsonins make an invading microorganism more susceptible to phagocytosisverifiedMay 18, 2026
Opt-Innounan individual makes an active affirmative indication of choice via a user interface signaling a desire to share their information with third parties.RequirementRegulatedPIIMay 18, 2026
Opt-Outnounan individual makes an active affirmative indication of choice via a user interface signaling a desire not to share their information with third parties.RequirementRegulatedPIIMay 18, 2026
Optative MoodnounMWEa mood (as in Greek or Sanskrit) that expresses a wish or hopeverifiedMay 18, 2026
Optic AxisnounMWEa line that passes through the center of curvature of a lens so that light is neither reflected nor refractedverifiedMay 18, 2026
Optic ChiasmnounMWEthe crossing of the optic nerves from the two eyes at the base of the brainverifiedMay 18, 2026
Optic ChiasmanounMWEthe crossing of the optic nerves from the two eyes at the base of the brainverifiedMay 18, 2026
Optic CupnounMWE(embryology) a two-walled cuplike depression that develops into the pigmented and sensory layers of the retinaverifiedMay 18, 2026
Optic DiscnounMWEthe point where the optic nerve enters the retinaverifiedMay 18, 2026
Optic DisknounMWEthe point where the optic nerve enters the retinaverifiedMay 18, 2026
Optic NervenounMWEthe cranial nerve that serves the retinaverifiedMay 18, 2026
Optic RadiationnounMWEa nerve pathway from the lateral geniculate body to the visual cortexverifiedMay 18, 2026
Optic TractnounMWEthe cranial nerve that serves the retinaverifiedMay 18, 2026
Optical AberrationnounMWEan optical phenomenon resulting from the failure of a lens or mirror to produce a good imageverifiedMay 18, 2026
Optical BenchnounMWEapparatus for observation and measurement of optical phenomenaverifiedMay 18, 2026
Optical CondensernounMWElens used to concentrate light on an objectverifiedMay 18, 2026
Optical CrownnounMWEoptical glass of low dispersion and low refractive indexverifiedMay 18, 2026
Optical Crown GlassnounMWEoptical glass of low dispersion and low refractive indexverifiedMay 18, 2026
Optical DensitynounMWE(physics) a measure of the extent to which a substance transmits light or other electromagnetic radiationverifiedMay 18, 2026
Optical DevicenounMWEa device for producing or controlling lightverifiedMay 18, 2026
Optical DiscnounMWEa disk coated with plastic that can store digital data as tiny pits etched in the surfaceverifiedMay 18, 2026
Optical DisknounMWEa disk coated with plastic that can store digital data as tiny pits etched in the surfaceverifiedMay 18, 2026