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Glossary · Nouns · O

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TermTypeDefinitionClassificationsUpdated
Ox-Eyed DaisynounMWEtall leafy-stemmed Eurasian perennial with white flowersverifiedMay 18, 2026
Oxacillinnouna form of penicillin resistant to penicillinase and effective against penicillin-resistant staphylococciverifiedMay 18, 2026
Oxalacetatenouna salt or ester of oxalacetic acidverifiedMay 18, 2026
Oxalacetic AcidnounMWEan acid formed by oxidation of maleic acid (as in metabolism of fats and carbohydrates)verifiedMay 18, 2026
Oxalatenouna salt or ester of oxalic acidverifiedMay 18, 2026
Oxalic AcidnounMWEa toxic colorless crystalline organic acid found in oxalis and other plantsverifiedMay 18, 2026
Oxalisnounany plant or flower of the genus OxalisverifiedMay 18, 2026
Oxaloacetatenouna salt or ester of oxalacetic acidverifiedMay 18, 2026
Oxaloacetic AcidnounMWEan acid formed by oxidation of maleic acid (as in metabolism of fats and carbohydrates)verifiedMay 18, 2026
Oxaprozinnouna nonsteroidal anti-inflammatory drug (trade name Daypro)verifiedMay 18, 2026
Oxazepamnouna tranquilizing drug (trade name Serax) used to treat anxiety and insomnia and alcohol withdrawalverifiedMay 18, 2026
Oxblood RednounMWEa dark brownish-red colorverifiedMay 18, 2026
Oxbownouna wooden framework bent in the shape of a UverifiedMay 18, 2026
Oxbow LakenounMWEa crescent-shaped lake (often temporary) that is formed when a meander of a river is cut off from the main channelverifiedMay 18, 2026
Oxbridgenoungeneral term for an ancient and prestigious and privileged university (especially Oxford University or Cambridge University)verifiedMay 18, 2026
Oxcartnouna cart that is drawn by an oxverifiedMay 18, 2026
Oxeyenounany North American shrubby perennial herb of the genus Heliopsis having large yellow daisylike flowersverifiedMay 18, 2026
Oxeye DaisynounMWEtall leafy-stemmed Eurasian perennial with white flowersverifiedMay 18, 2026
Oxfordnouna low shoe laced over the instepverifiedMay 18, 2026
Oxford GraynounMWEa very dark grey colorverifiedMay 18, 2026
Oxford GreynounMWEa very dark grey colorverifiedMay 18, 2026
Oxheartnounany of several cultivated sweet cherries having sweet juicy heart-shaped fruitsverifiedMay 18, 2026
Oxheart CherrynounMWEany of several cultivated sweet cherries having sweet juicy heart-shaped fruitsverifiedMay 18, 2026
Oxidantnouna substance that oxidizes another substanceverifiedMay 18, 2026
Oxidasenounany of the enzymes that catalyze biological oxidationverifiedMay 18, 2026
Oxidationnounthe process of oxidizingverifiedMay 18, 2026
Oxidation NumbernounMWEthe degree of oxidation of an atom or ion or moleculeverifiedMay 18, 2026
Oxidation StatenounMWEthe degree of oxidation of an atom or ion or moleculeverifiedMay 18, 2026
Oxidation-Reductionnouna reversible chemical reaction in which one reaction is an oxidation and the reverse is a reductionverifiedMay 18, 2026
Oxidation-Reduction IndicatornounMWEan indicator that shows a reversible color change between oxidized and reduced formsverifiedMay 18, 2026
Oxidative PhosphorylationnounMWEan enzymatic process in cell metabolism that synthesizes ATP from ADPverifiedMay 18, 2026
Oxidenounany compound of oxygen with another element or a radicalverifiedMay 18, 2026
Oxidisationnounthe process of oxidizingverifiedMay 18, 2026
Oxidisernouna substance that oxidizes another substanceverifiedMay 18, 2026
Oxidizationnounthe process of oxidizingverifiedMay 18, 2026
Oxidized LDL CholesterolnounMWELDL cholesterol that has been bombarded by free radicalsverifiedMay 18, 2026
Oxidizernouna substance that oxidizes another substanceverifiedMay 18, 2026
Oxidizing AgentnounMWEa substance that oxidizes another substanceverifiedMay 18, 2026
Oxidoreductasenounan enzyme that catalyzes oxidation-reductionverifiedMay 18, 2026
Oxidoreductionnouna reversible chemical reaction in which one reaction is an oxidation and the reverse is a reductionverifiedMay 18, 2026
Oximenounany compound containing the group -C=NOHverifiedMay 18, 2026
Oximeternouna measuring instrument that measures the oxygen in arterial bloodverifiedMay 18, 2026
OxlipnounEurasian primrose with yellow flowers clustered in a one-sided umbelverifiedMay 18, 2026
Oxtailnounthe skinned tail of cattleverifiedMay 18, 2026
Oxtail SoupnounMWEa soup made from the skinned tail of an oxverifiedMay 18, 2026
Oxtantnouna unit of angular distance equal to half a quadrantverifiedMay 18, 2026
Oxtonguenounwidespread European weed with spiny tongue-shaped leaves and yellow flowersverifiedMay 18, 2026
Oxyacetylenenouna mixture of oxygen and acetyleneverifiedMay 18, 2026
Oxyacetylene TorchnounMWEa blowtorch that burns oxyacetyleneverifiedMay 18, 2026
Oxyacidnounany acid that contains oxygenverifiedMay 18, 2026
Oxybenzenenouna toxic white soluble crystalline acidic derivative of benzeneverifiedMay 18, 2026
Oxybutyric AcidnounMWEhydroxy derivative of butyric acidverifiedMay 18, 2026
Oxycephalynouna congenital abnormality of the skullverifiedMay 18, 2026
Oxygennouna nonmetallic bivalent element that is normally a colorless odorless tasteless nonflammable diatomic gasverifiedMay 18, 2026
Oxygen AcidnounMWEany acid that contains oxygenverifiedMay 18, 2026
Oxygen DebtnounMWEa cumulative deficit of oxygen resulting from intense exerciseverifiedMay 18, 2026
Oxygen DeficitnounMWEtemporary oxygen shortage in cells resulting from strenuous exerciseverifiedMay 18, 2026
Oxygen MasknounMWEa breathing device that is placed over the mouth and noseverifiedMay 18, 2026
Oxygenasenounan oxidoreductase that catalyzes the incorporation of molecular oxygenverifiedMay 18, 2026
Oxygenationnounthe process of providing or combining or treating with oxygenverifiedMay 18, 2026
Oxyhaemoglobinnounthe bright red hemoglobin that is a combination of hemoglobin and oxygen from the lungsverifiedMay 18, 2026
Oxyhemoglobinnounthe bright red hemoglobin that is a combination of hemoglobin and oxygen from the lungsverifiedMay 18, 2026
Oxymoronnounconjoining contradictory terms (as in `deafening silence')verifiedMay 18, 2026
Oxyopianoununusually acute visionverifiedMay 18, 2026
Oxyphenbutazonenounan anti-inflammatory drug (trade name Tandearil) used to treat arthritis and bursitisverifiedMay 18, 2026
Oxyphencycliminenounan anticholinergic drug (trade name Daricon) used in treating peptic ulcersverifiedMay 18, 2026
Oxytocicnouna drug that induces labor by stimulating contractions of the muscles of the uterusverifiedMay 18, 2026
Oxytocic DrugnounMWEa drug that induces labor by stimulating contractions of the muscles of the uterusverifiedMay 18, 2026
Oxytocinnounhormone secreted by the posterior pituitary gland (trade name Pitocin)verifiedMay 18, 2026
Oxytonenounword having stress or an acute accent on the last syllableverifiedMay 18, 2026
Oyabunnouna Japanese supervisorverifiedMay 18, 2026
Oyster AgaricnounMWEedible agaric with a soft greyish cap growing in shelving masses on dead woodverifiedMay 18, 2026
Oyster BanknounMWEa workplace where oysters are bred and grownverifiedMay 18, 2026
Oyster BarnounMWEa restaurant that specializes in oysters prepared in different waysverifiedMay 18, 2026
Oyster BednounMWEa workplace where oysters are bred and grownverifiedMay 18, 2026
Oyster CrabnounMWEtiny soft-bodied crab living within the mantle cavity of oystersverifiedMay 18, 2026
Oyster CrackernounMWEa small dry usually round crackerverifiedMay 18, 2026
Oyster DressingnounMWEstuffing made with oystersverifiedMay 18, 2026
Oyster FishnounMWEa variety of toadfishverifiedMay 18, 2026
Oyster FungusnounMWEedible agaric with a soft greyish cap growing in shelving masses on dead woodverifiedMay 18, 2026
Oyster MushroomnounMWEedible agaric with a soft greyish cap growing in shelving masses on dead woodverifiedMay 18, 2026
Oyster ParknounMWEa workplace where oysters are bred and grownverifiedMay 18, 2026
Oyster PlantnounMWEMediterranean biennial herb with long-stemmed heads of purple ray flowers and milky sap and long edible rootverifiedMay 18, 2026
Oyster ShellnounMWEa shell of an oysterverifiedMay 18, 2026
Oyster StewnounMWEoysters in creamverifiedMay 18, 2026
Oyster StuffingnounMWEstuffing made with oystersverifiedMay 18, 2026
Oystercatchernounblack-and-white shorebird with stout legs and billverifiedMay 18, 2026
Oysters RockefellernounMWEoysters spread with butter and spinach and seasonings and baked on the half shellverifiedMay 18, 2026
Oz.nouna unit of weight equal to one sixteenth of a pound or 16 drams or 28.349 gramsverifiedMay 18, 2026
Ozaenanouna chronic disease of the nose characterized by a foul-smelling nasal discharge and atrophy of nasal structuresverifiedMay 18, 2026
Ozark HarpnounMWEa small lyre-shaped musical instrument that is placed between the teeth and played by twanging a wire tongue while changing the shape of the mouth cavityverifiedMay 18, 2026
Ozenanouna chronic disease of the nose characterized by a foul-smelling nasal discharge and atrophy of nasal structuresverifiedMay 18, 2026
Ozoceritenouna waxy mineral that is a mixture of hydrocarbons and occurs in association with petroleumverifiedMay 18, 2026
Ozokeritenouna waxy mineral that is a mixture of hydrocarbons and occurs in association with petroleumverifiedMay 18, 2026
Ozonenouna colorless gas (O3) soluble in alkalis and cold waterverifiedMay 18, 2026
Ozone HolenounMWEan area of the ozone layer (near the poles) that is seasonally depleted of ozoneverifiedMay 18, 2026
Ozone LayernounMWEa layer in the stratosphere (at approximately 20 miles) that contains a concentration of ozone sufficient to block most ultraviolet radiation from the sunverifiedMay 18, 2026
Ozone SicknessnounMWEillness that can occur to persons exposed to ozone in high-altitude aircraftverifiedMay 18, 2026
Ozonidenounany of a class of unstable chemical compounds resulting from the addition of ozone to a double bond in an unsaturated compoundverifiedMay 18, 2026
Ozonospherenouna layer in the stratosphere (at approximately 20 miles) that contains a concentration of ozone sufficient to block most ultraviolet radiation from the sunverifiedMay 18, 2026