English Words: O
15,494 words · Page 299 of 310
One of the constituents of the citric acid cycle, formed by the oxidation of malic acid and via the transamination of aspartic acid; an intermediate in the synthesis of amino acids and the metabolism of carbohydrates
Any of several oxalo- derivatives of crotonic acid, but especially 4-oxalocrotonic acid, COOH-CO-CH₂-CH=CH-COOH, which has a biochemical function.
The presence of oxalic acid and oxalate in the urine (which is often true, in some amount or other).
A complex nitrogenous acid related to the ureids, and obtained from parabanic acid as a white silky crystalline substance.
Either the univalent or the divalent radicals derived from oxalic acid by removal of one or two hydrogen atoms
An amide formed from condensation of oxalic acid and the amino group of glycine; it is an inhibitor of some classes of enzymes
One of a series of bases containing the amido and isonitroso groups united to the same carbon atom.
An androgenic anabolic steroid C₁₉H₃₀O₃ administered orally especially to promote weight gain (as after extensive surgery or a chronic infection) and to relieve bone pain in osteoporosis.
A white crystalline substance resembling oxanilamide, obtained by heating aniline oxalate, and regarded as a double anilide of oxalic acid; diphenyl oxamide.
Any of several oxygen-containing heterocycles derived from norbornene, especially those that are used to make polymers
An ether formally formed from pentane by replacing a methylene group by an oxygen atom
The six-membered unsaturated heterocycle containing four carbon atoms, one oxygen atom, one phosphorus atom and two double bonds
The unsaturated five-membered heterocycle having three carbon atoms, one oxygen atom, one phosphorus atom and two double bonds.
A saturated five-membered heterocycle having three carbon atoms, one silicon and one oxygen atom; any of its derivatives
Any of three isomeric six-membered saturated heterocycles containing four carbon atoms, one oxygen and one sulfur atom
A six-membered unsaturated heterocycle containing three carbon atoms and one each of nitrogen, oxygen and sulfur
A six-membered unsaturated heterocycle containing three carbon atoms (one of them as a carbonyl group) and one each of nitrogen, oxygen and sulfur
The unsaturated five-membered heterocycle having two carbon atoms, one oxygen atom, one sulfur atom, one nitrogen atom and one double bond
A five-membered, saturated heterocycle having two carbon atoms, and one each of nitrogen, sulfur and oxygen; any derivative of this compound
The unsaturated six-membered heterocycle having four carbon atoms, one oxygen atom, one sulfur atom and two double bonds
A saturated three-membered heterocycle containing one carbon, one sulfur and one oxygen atoms
Any five-membered heterocycle having one carbon atom, three nitrogen atoms, one oxygen atom, and two double bonds
A saturated five-membered heterocycle having two carbon atoms, and one each of oxygen, nitrogen and phosphorus
Any saturated six-membered heterocycle containing three carbon atoms and one each of oxygen, nitrogen and phosphorus, especially one in which the phosphorus atom is linked to both the nitrogen and oxygen atoms
A drug of the benzodiazepine group, used to treat anxiety states and insomnia; 7-chloro-1,3-dihydro-3-hydroxy-5-phenyl-1,4-benzodiazepin-2-one, C₁₅H₁₁ClN₂O₂.
A three-membered saturated heterocycle having one carbon, one nitrogen and one oxygen atoms
A benzodiazepine drug with anxiolytic, anticonvulsant, sedative and skeletal muscle relaxant properties.
Spelling & Dictionary Insight
The English alphabetical index for the letter O contains 15,494 headwords drawn from our Wiktionary-derived dictionary table. At 50 entries per page the browse splits into 310 pages, and you are currently viewing page 299. Every row above is a dictionary-backed entry with a canonical slug, and each links through to a full definition page with pronunciation, senses, etymology, and related-word data where available.
On this page 50 of 50 entries carry a part-of-speech tag and 50 carry at least one stored definition. Coverage varies across letters because Wiktionary volunteers build entries at different speeds for different parts of the alphabet, letters with common starting sounds (S, C, T, P) usually have the densest coverage, while less frequent starters (X, Q, Z) tend to have shorter but more specialised lists. PlainSpell surfaces whatever data is present and links back to the source when a definition is not yet recorded.
For readers using this index as a spelling reference, the guarantee is that every form you see on the list is a documented English headword, not a guess, not a derived inflection lacking a lemma row. If a word you expected to find is absent from the "O" list, it usually means the form exists only as an inflection of another lemma (e.g. a past participle stored under the infinitive) or the entry has not yet been imported from Wiktionary. Use the search bar or the misspelling lookup to resolve these cases.