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Glossary · Nouns · O

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TermTypeDefinitionClassificationsUpdated
One Thousand MillionnounMWEthe number that is represented as a one followed by 9 zerosverifiedMay 18, 2026
One Thousand ThousandnounMWEthe number that is represented as a one followed by 6 zerosverifiedMay 18, 2026
One-And-Onenouna foul shot that must be made in order to earn the right to a second foul shotverifiedMay 18, 2026
One-Armed BanditnounMWEa slot machine that is used for gamblingverifiedMay 18, 2026
One-Billionthnounone part in a billion equal partsverifiedMay 18, 2026
One-Dimensional LanguagenounMWEa programming language whose expressions are represented by strings of charactersverifiedMay 18, 2026
One-Dimensionalitynounthe property of having one dimensionverifiedMay 18, 2026
One-Eighthnounone part in eight equal partsverifiedMay 18, 2026
One-Fifthnounone part in five equal partsverifiedMay 18, 2026
One-Flowered PyrolanounMWEdelicate evergreen dwarf herb of north temperate regions having a solitary white terminal flowerverifiedMay 18, 2026
One-Flowered WintergreennounMWEdelicate evergreen dwarf herb of north temperate regions having a solitary white terminal flowerverifiedMay 18, 2026
One-Fourthnounone of four equal partsverifiedMay 18, 2026
One-Halfnounone of two equal parts of a divisible wholeverifiedMay 18, 2026
One-Hitternouna game in which a pitcher allows the opposing team only one hitverifiedMay 18, 2026
One-Hundred-Millionthnounone part in a hundred million equal partsverifiedMay 18, 2026
One-Hundred-Thousandthnounone part in a hundred thousand equal partsverifiedMay 18, 2026
One-Hundredthnounone part in a hundred equal partsverifiedMay 18, 2026
One-Linernouna one-line jokeverifiedMay 18, 2026
One-Man RulenounMWEa form of government in which the ruler is an absolute dictator (not restricted by a constitution or laws or opposition etc.)verifiedMay 18, 2026
One-Millionthnounone part in a million equal partsverifiedMay 18, 2026
One-Night StandnounMWEa brief sexual encounter lasting only for a single nightverifiedMay 18, 2026
One-Ninthnounone part in nine equal partsverifiedMay 18, 2026
One-Offnouna happening that occurs only once and is not repeatedverifiedMay 18, 2026
One-part CodenounMWECode in which plain text elements and their accompanying code groups are arranged in alphabetical, numerical, or other systematic order, so one listing serves for both encoding and decoding. One-part codes are normally small codes used to pass small volumes of low-sensitivity information.ArtifactMay 12, 2026
One-Quadrillionthnounone part in a quadrillion equal partsverifiedMay 18, 2026
One-Quarternounone of four equal partsverifiedMay 18, 2026
One-Quintillionthnounone part in a quintillion equal partsverifiedMay 18, 2026
One-Seventhnounone part in seven equal partsverifiedMay 18, 2026
One-Sixteenthnounone part in sixteen equal partsverifiedMay 18, 2026
One-Sixthnounone part in six equal partsverifiedMay 18, 2026
One-Sixtiethnounone part in sixty equal partsverifiedMay 18, 2026
One-Sixty-Fourthnounone part in sixty-four equal partsverifiedMay 18, 2026
One-Spotnouna domino or die whose upward face shows one pipverifiedMay 18, 2026
One-Stepnounan early ballroom danceverifiedMay 18, 2026
One-Ten-Thousandthnounone part in ten thousand equal partsverifiedMay 18, 2026
One-Tenthnouna tenth partverifiedMay 18, 2026
One-Thirdnounone of three equal parts of a divisible wholeverifiedMay 18, 2026
One-Thirty-Secondnounone part in thirty-two equal partsverifiedMay 18, 2026
One-Thousandthnounone part in a thousand equal partsverifiedMay 18, 2026
One-time CryptosystemnounMWECryptosystem employing key used only once.ControlMay 9, 2026
One-time PadnounMWEManual one-time cryptosystem produced in pad form.CredentialRestrictedCUIMay 9, 2026
One-time TapenounMWEPunched paper tape used to provide key streams on a one-time basis in certain machine cryptosystems.PhysicalRegulatedCUIMay 9, 2026
One-Trillionthnounone part in a trillion equal partsverifiedMay 18, 2026
One-Twelfthnounone part in twelve equal partsverifiedMay 18, 2026
One-Upmanshipnounthe practice of keeping one jump ahead of a friend or competitorverifiedMay 18, 2026
One-Way EncryptionnounMWEIrreversible transformation of plaintext to cipher text, such that the plaintext cannot be recovered from the cipher text by other than exhaustive procedures even if the cryptographic key is known.ControlMay 9, 2026
One-Way FunctionnounMWEA (mathematical) function, f, which is easy to compute the output based on a given input. However given only the output value it is impossible (except for a brute force attack) to figure out what the input value is.ControlMay 9, 2026
One-Way Hash AlgorithmnounMWEHash algorithms which map arbitrarily long inputs into a fixed-size output such that it is very difficult (computationally infeasible) to find two different hash inputs that produce the same output. Such algorithms are an essential part of the process of producing fixed-size digital signatures that can both authenticate the signer and provide for data integrity checking (detection of input modification after signature).ControlMay 9, 2026
One-Way Light TimenounMWEthe elapsed time it takes for light (or radio signals) to travel between the Earth and a celestial objectverifiedMay 18, 2026
One-Way StreetnounMWEa street on which vehicular traffic is allowed to move in only one directionverifiedMay 18, 2026
Oneirismnounabsentminded dreaming while awakeverifiedMay 18, 2026
Oneiromancernounsomeone who divines through the interpretation of dreamsverifiedMay 18, 2026
Oneiromancynoundivination through the interpretation of dreamsverifiedMay 18, 2026
Onenessnounthe quality of being united into oneverifiedMay 18, 2026
Onerousnessnoununwelcome burdensome difficultyverifiedMay 18, 2026
Onionnounbulbous plant having hollow leaves cultivated worldwide for its rounded edible bulbverifiedMay 18, 2026
Onion BagelnounMWEbagel flavored with onionverifiedMay 18, 2026
Onion BreadnounMWEbread containing finely minced onionsverifiedMay 18, 2026
Onion ButternounMWEbutter blended with minced onionverifiedMay 18, 2026
Onion DomenounMWEa dome that is shaped like a bulbverifiedMay 18, 2026
Onion LousenounMWEinjurious to onion plants and sometimes tobaccoverifiedMay 18, 2026
Onion MildewnounMWEfungus causing a downy mildew on onionsverifiedMay 18, 2026
Onion PlantnounMWEbulbous plant having hollow leaves cultivated worldwide for its rounded edible bulbverifiedMay 18, 2026
Onion RollnounMWEyeast-raised roll flavored with onionverifiedMay 18, 2026
Onion SaltnounMWEground dried onion and saltverifiedMay 18, 2026
Onion SmutnounMWEsmut fungus causing blackish blisters on scales and leaves of onionsverifiedMay 18, 2026
Onion StemnounMWEa white agaric that tends to cluster and has a club-shaped baseverifiedMay 18, 2026
Onion ThripsnounMWEinjurious to onion plants and sometimes tobaccoverifiedMay 18, 2026
Onion Yellow DwarfnounMWEthe yellow dwarf disease of onion plantsverifiedMay 18, 2026
Onion Yellow-Dwarf VirusnounMWEthe virus that produces stunting and yellowing of the leaves of onion plantsverifiedMay 18, 2026
Onionskinnouna thin strong lightweight translucent paper used especially for making carbon copiesverifiedMay 18, 2026
Online AttacknounMWEAn attack against an authentication protocol where the Attacker either assumes the role of a Claimant with a genuine Verifier or actively alters the authentication channel. The goal of the attack may be to gain authenticated access or learn authentication secrets.ThreatRegulatedMay 12, 2026
Online Certificate Status ProtocolnounMWEAn online protocol used to determine the status of a public key certificate.CredentialMay 9, 2026
Online CryptosystemnounMWECryptographic system in which encryption and decryption are performed in association with the transmitting and receiving functions.CapabilityRegulatedMay 12, 2026
Online LearningnounMWEfitting [one's] model incrementally as the data flows in (streaming data).ProcessMay 18, 2026
online terminalnounMWEA web-browser-based access to an acquirer, processor or third party service provider website to authorize payment card transactions, where the merchant manually enters payment card data via a securely connected web browser. Unlike physical terminals, virtual payment terminals do not read data directly from a payment card. Because payment card transactions are entered manually, virtual payment terminals are typically used instead of physical terminals in merchant environments with low transaction volumes.SystemRegulatedPCIMay 9, 2026
Onlookernounsomeone who looks onverifiedMay 18, 2026
Onomancernounone who practices onomancyverifiedMay 18, 2026
Onomancynoundivination by the letters of a nameverifiedMay 18, 2026
Onomasticonnouna list of proper nouns naming persons or placesverifiedMay 18, 2026
Onomasticsnounthe branch of lexicology that studies the forms and origins of proper namesverifiedMay 18, 2026
Onomatomanianounobsession with a particular word which the person uses repeatedly or which intrudes into consciousnessverifiedMay 18, 2026
Onomatopoeianounusing words that imitate the sound they denoteverifiedMay 18, 2026
Onrushnoun(military) an offensive against an enemy (using weapons)verifiedMay 18, 2026
Onsetnoun(military) an offensive against an enemy (using weapons)verifiedMay 18, 2026
Onslaughtnounthe rapid and continuous delivery of linguistic communication (spoken or written)verifiedMay 18, 2026
Ontogenesisnoun(biology) the process of an individual organism growing organicallyverifiedMay 18, 2026
Ontogenynoun(biology) the process of an individual organism growing organicallyverifiedMay 18, 2026
OntologynounA set of concepts and categories in a subject area or knowledge domain that shows their properties and the relationships among them to enable interoperability among disparate elements and systems and specify interfaces to independent, knowledge-based services for the purpose of enabling certain kinds of automated reasoning.ArtifactMay 18, 2026
Onusnounan onerous or difficult concernverifiedMay 18, 2026
Onward MotionnounMWEthe act of moving forward (as toward a goal)verifiedMay 18, 2026
Onycholysisnounseparation of a nail from its normal attachment to the nail bedverifiedMay 18, 2026
Onychophorannounany of numerous velvety-skinned wormlike carnivorous animals common in tropical forests having characteristics of both arthropods and annelid wormsverifiedMay 18, 2026
Onychosisnounany disease or disorder of the nailsverifiedMay 18, 2026
Onyxnouna chalcedony with alternating black and white bandsverifiedMay 18, 2026
Onyx MarblenounMWEa hard compact kind of calciteverifiedMay 18, 2026
Onyxisnountoenail having its free tip or edges embedded in the surrounding fleshverifiedMay 18, 2026
Oocytenouna female gametocyte that develops into an ovum after two meiotic divisionsverifiedMay 18, 2026
Oodlesnouna large number or amountverifiedMay 18, 2026
Oogenesisnoundevelopment of ovaverifiedMay 18, 2026