English words: octadecahedral to octodecimo

300 English words, part 7 of 67 of the words starting with O, A to Z. 14 have a page of their own.

English words octadecahedral to octodecimo

octadecahedral adjective: In the form of an octadecahedron.
octadecahedron noun: A polyhedron with eighteen faces.
octadecahydrate noun: Eighteen water molecules in a hydrated compound.
octadecamer noun: An oligomer having eighteen subunits.
octadecameric adjective: Of or pertaining to an octadecamer.
octadecanal noun: The aliphatic aldehyde that has 18 carbon atoms
octadecanamide noun: The acid amide of octadecanoic acid
octadecane noun: Any of very many isomeric alkanes having the formula C₁₈H₃₈, but especially n-octadecane CH₃(CH₂)₁₆CH₃.
octadecanethiol noun: The aliphatic thiol that has 18 carbon atoms
octadecanoate noun: Any salt or ester of octadecanoic acid
octadecanoic adjective: Of or pertaining to octadecanoic acid or its derivatives
octadecanoic acid noun: Synonym of stearic acid.
octadecanoid noun: Relating to octadecanoic acid and its derivatives, but especially to polyunsaturated forms that are involved in the biosynthesis of jasmonic acid
octadecanol noun: Any saturated aliphatic alcohol that has eighteen carbon atoms, but especially 1-octadecanol
octadecanoyl noun: The univalent radical derived from octadecanoic acid by loss of the hydroxy group; stearoyl
octadecapeptide noun: A polypeptide containing eighteen amino acid moieties
octadecatetraenoate noun: Any salt or ester of an octadecatetraenoic acid
octadecatetraenoic adjective: Of or pertaining to octadecatetraenoic acid or its derivatives; stearidonic
octadecatetraenoic acid noun: stearidonic acid
octadecatrienoic adjective: Of or pertaining to octadecatrienoic acid or its derivatives; linolenic.
octadecatrienoic acid noun: linolenic acid, eleostearic acid, calendic acid or other isomer of a trienoic fatty acid with 18 carbon atoms
octadecatrienol noun: An aliphatic alcohol that has eighteen carbon atoms and three double bonds
octadecatrienoyl noun: The univalent radical derived from octadecatrienoic acid by loss of the hydroxy group; linolenoyl
octadecene noun: Any of very many isomers of an alkene having eighteen carbon atoms and one double bond
octadecenoate noun: Any salt or ester of octadecenoic acid; oleate.
octadecenoic adjective: Of or pertaining to octadecenoic acid or its derivatives; oleic.
octadecenoic acid noun: oleic acid
octadecenol noun: Any of many isomeric aliphatic alcohols that have eighteen carbon atoms and a double bond
octadecenoyl noun: The univalent radical derived from octadecenoic acid by loss of the hydroxy group; oleoyl
octadecyl noun: Any of very many isomeric univalent hydrocarbon radicals, C₁₈H₃₇, formally derived from an octadecane by the loss of a hydrogen atom
octadecylamine noun: Any of very many isomeric amines derived from an octadecane, but especially the primary amine CH₃(CH₂)₁₇NH₂
octadecylsilane noun: A surface coating used in reversed-phase chromatography.
octadecyne noun: Any aliphatic hydrocarbon having a chain of eighteen carbon atoms and containing one triple bond.
octadehydrocorrin noun: corrole
octadentate adjective: Of a ligand, capable of forming eight separate chemical bonds to a coordinating metal ion
octadepsipeptide noun: An oligomeric form of depsipeptide composed of eight monomers
octadic adjective: of or pertaining to an octad; eightfold
octadienal noun: Any of several isomeric unsaturated aliphatic aldehyde having eight carbon atoms and two double bonds.
octadiene noun: Any of several isomeric dienes having eight carbon atoms
octadrachm noun: An Ancient Greek coin having a value of eight drachmas.
octaedron noun: Alternative spelling of octahedron.
octaeteric adjective: Synonym of octennial (“related to or characterized by an eight-year period”)
octaeteris noun /ˌɑktaɪˈtɪɹɪs/: Synonym of octennium: An 8-year period, particularly (historical) in Greek calendrical and astronomical calculations.
octaethyl noun: Eight ethyl groups in a molecule
octaethylene glycol noun: A short-chain polyethylene glycol made of eight ethylene oxide units with a hydroxyl group at each end. It is a water-soluble, flexible polyether used...
octaethyleneglycol noun: Alternative form of octaethylene glycol.
octaethylporphyrin noun: A synthetic porphyrin compound with eight ethyl groups on its ring structure. It forms a stable, aromatic macrocycle that can bind metals and is commonly...
octafinal noun: The round in eliminations preceding the quarterfinal round; in single-elimination playoffs, this is the round of 16.
octafluoride noun: any fluoride containing eight fluorine atoms in each molecule
octafluoro noun: Eight fluorine atoms in a compound.
octafluorocyclobutane noun: The organofluorine compound C₄F₈, related to cyclobutane by replacement of all C–H bonds with C–F bonds, and used as a deposition gas and etchant in...
octafluoropropane noun: The fluorocarbon perfluoropropane; a greenhouse gas used in plasma etching, refrigeration, and ultrasound
octaglucoside noun: Any glucoside that has eight glucose units
octaglutamate noun: Any compound that has eight glutamate groups or anions
octagon noun /ˈɒktəɡ(ə)n/: A polygon with eight sides and eight angles.
octagonal adjective /ɑkˈtæɡənəl/: Shaped like an octagon, in having eight sides and eight angles.
octagonally adverb: In an octagonal manner.
octagonian adjective, noun /ˌɒk.təˈɡəʊ.ni.ən/: Relating to an octagon
octagram noun /ˈɒk.tə.ɡɹæm/: An eight-sided star polygon.
octagynous adjective: Alternative form of octogynous.
octahedral adjective: Of, relating to, or having the shape of an octahedron.
octahedrality noun: The state or condition of being octahedral.
octahedrally adverb: In an octahedral manner
octahedrane noun: A hypothetical paddlane derivative, in the form of an octahedron, that would be an allotrope of carbon
octahedric adjective: Alternative form of octahedral.
octahedrical adjective: octahedral
octahedrite noun: The mineral anatase.
octahedron noun: a polyhedron with eight faces; the regular octahedron has regular triangles as faces and is one of the Platonic solids.
octahedrous adjective: octahedral
octaheme noun: Eight heme groups in a hemoprotein
octahemioctahedron noun: A nonconvex uniform polyhedron that has 12 faces, 24 edges and 12 vertices.
octahistidine noun: polyhistidine that has eight monomers
octahydrate noun: A hydrate whose solid contains eight molecules of water of crystallization per molecule, or per unit cell.
octahydride noun: Any hydride containing eight atoms of hydrogen per molecule
octahydrochloride noun: Any compound that has eight hydrochloride groups
octahydrocurcumin noun: The metabolite of curcumin (3S,5S)-1,7-bis(4-hydroxy-3-methoxyphenyl)heptane-3,5-diol that shows anticancer activity
octahydrocurcuminoid noun: Synonym of octahydrocurcumin, and related compounds
octahydronaphthalene noun: A partially hydrogenated derivative of naphthalene with the molecular formula C₁₀H₁₆ and it consists of two fused six-membered carbon rings and contains one...
octahydroxy noun: Eight hydroxy functional groups in a molecule
octahydroxyanthraquinone noun: A highly hydroxylated organic compound derived from the anthraquinone molecule. It consists of an anthraquinone core with eight hydroxyl groups attached,...
octairon noun: Eight iron atoms or cations in a molecule (Fe₈)
octakaidecahedron noun: Synonym of octadecahedron.
octaketide noun: Any polyketide that has eight ketide groups
octakis- prefix: A variant of octo-, used for multiplication with a second numerical prefix: octakishexahedron
octakishexahedron noun: A polyhedron with 48 faces.
octal adjective, noun /ˈɒk.təl/: The number system that uses the eight digits 0, 1, 2, 3, 4, 5, 6, 7.
octal data rate noun: A memory interface which performs eight bits per clock cycle per lane
octalead noun: Eight atoms of lead in a chemical compound.
octalogue noun: A series of eight statements.
octalogy noun: A set of eight works of art that are connected, and that can be seen either as a single work or as eight individual works. They are commonly found in...
octaloop noun: An eight-base hairpin loop motif
octamanganese noun: Eight manganese atoms or cations in a molecule (Mn₈)
octamer noun: An oligomer having eight subunits.
octameric adjective: Of or pertaining to an octamer.
octamerisation noun: Alternative form of octamerization.
octamerism noun: The condition of being octamerous
octamerization noun: oligomerization that forms an octamer
octamerize verb: To form into an octamer
octamerized adjective, verb: Formed into an octamer
octamerous adjective: Having parts in groups of eight
octameter noun: A line of verse containing eight metrical feet
octamethyl noun: (in combination) eight methyl groups in a molecule
octamethylcyclotetrasiloxane noun /ˌɒk.təˌmɛθ.ɪlˌsaɪ.kloʊˌtɛt.rəˌsaɪ.lɒk.seɪn/: A cyclic silicone compound made of a ring of silicon and oxygen atoms with methyl groups attached. It’s mainly used as a raw material for making silicones...
octamethylene noun: Eight methylene groups in a molecule (typically in a row, with substituents or functional groups at each end)
octamethylpyrophosphoramide noun: A synthetic organophosphorus compound that was developed as an insecticide. It works by disrupting nerve function in insects by inhibiting...
octamethyltrisiloxane noun: A particular linear siloxane.
octamoxin noun: A hydrazine drug formerly used as an antidepressant.
octan adjective, noun: Occurring every eight days.
octanal noun: The saturated aliphatic aldehyde having eight carbon atoms.
octanaldehyde noun: Synonym of octanal.
octanamide noun: The acid amide of octanoic acid, CH₃CH₂CH₂CH₂CH₂CH₂CH₂CONH₂
octandrious adjective: Alternative form of octandrous.
octandrous adjective: Having eight stamens.
octane noun /ˈɒkteɪn/: Any of the eighteen isomeric aliphatic hydrocarbons (C₈H₁₈) found in petroleum, especially an iso-octane 2,2,4 trimethyl-pentane; they are used as fuels and...
octane number noun: A measure of the antiknock properties of an automobile fuel.
octane rating noun: An octane number.
octanedioic acid noun: Suberic acid.
octanedione noun: Any of several isomeric diketones, derived from octane, that are used as intermediates in organic synthesis
octanethiol noun: Any thiol derived from an octane, but especially 1-octanethiol
octangle noun /ˈɑk.tæŋ.ɡ(ə)l/: A geometric figure with eight corners, an octagon.
octangular adjective /ɑkˈtæŋ.ɡjə.lə(ɹ)/: Octagonal, with eight angles.
octangularly adverb: In an octangular manner.
octanitride noun: Any nitride containing eight atoms of nitrogen
octanitrocubane noun: A high explosive derived from cubane, and one of the most powerful chemical explosives known.
octanoate noun: Any salt or ester of octanoic acid.
octanoic adjective: Of or pertaining to octanoic acid or its derivatives
octanoic acid noun: caprylic acid
octanol noun: Any of many isomers of the saturated aliphatic alcohol having eight carbon atoms, but especially the simple primary alcohol n-octanol; its esters are used...
octanolysis noun: alcoholysis using octanol
octanone noun: Any aliphatic ketone that has eight carbon atoms
octanose noun: Any monosaccharide having the configuration of an eight-membered ring.
octanoyl noun: The univalent radical derived from octanoic acid by loss of the hydroxy group; capryloyl
octanoylate verb: To cause or to undergo octanoylation
octanoylated adjective: reacted with octanoic acid
octanoylation noun: reaction with octanoic acid (to form an octanoate)
octanoylcarnitine noun: The N-octanoyl derivative of carnitine
octanoyltransferase noun: Any transferase that transfers octanoyl groups
octant noun: The eighth part of a circle; an arc of 45 degrees.
octantal adjective: Relating to an octant.
octantimonide noun: Eight antimonide ions in a molecule (Sb₈)
octanucleate adjective: Having eight nuclei.
octanucleotide noun: A codon containing eight nucleotides.
octaose noun: Any oligosaccharide containing eight monosaccharide moieties
octaoxide noun: Alternative form of octoxide.
octaoxo noun: A chemical compound with eight oxygen atoms with double bonds.
octaoxygen noun: A red allotrope of oxygen, O₈, that is stable only under very high pressures
octapalladium noun: Eight palladium atoms or cations in a molecule (Pd₈)
octapartite adjective: divided into eight parts
octapeptide noun: An oligopeptide having eight amino acids.
octaphosphorus noun: eight atoms of phosphorus in a compound
octaples noun: Synonym of octapla.
octaploid adjective, noun: Alternative form of octoploid.
octaploidy noun: Alternative form of octoploidy.
octapody noun: A metre or verse of eight feet.
octapolar adjective: That employs eight electrodes
octapole noun: Alternative form of octupole.
octaprenyl noun: Formed from eight isoprene units
octaqua noun: Eight water molecules in a compound.
octarch adjective: Having eight strands of xylem
octarchic adjective: Of or relating to octarchy.
octarchy noun: A group of eight states.
octarepeat noun: A sequence of octapeptides that are repeated in a polypeptide or protein
octarhodium noun: Eight rhodium atoms or cations in a molecule (Rh₈)
octarine noun: The color of magic, a notional extra color distinct from the colors of the rainbow / normal visible light spectrum, which is said (chiefly in certain...
octarius noun /ɒkˈtɛəɹi.əs/: The pint (eighth of a gallon) in the apothecaries' system.
octaroon noun: Alternative spelling of octoroon.
octarticulate adjective: Having eight joints or articulations
octary adjective: Synonym of octal.
octasaccharide noun: An oligosaccharide that has eight sugar units
octasaccharidic adjective: Relating to an octasaccharide
octasilicate noun: Eight silicate anions or groups in a molecule.
octasiloxane noun: Any siloxane having eight -Si-O- groups
octasilver noun: Eight silver atoms or ions in a compound (Ag₈).
octasodium noun: Eight sodium atoms or cations in a molecule
octasome noun: Any one of eight homologous chromosomes in an aneuploid complement
octastich noun: A poem or strophe of eight verses or lines.
octastichous adjective: Having a phyllotaxis of eight leaves in each spiral around a stem
octastyle adjective, noun: Having eight columns in the front row (of a portico etc.)
octastylos noun: Synonym of octastyle.
octasulfane noun: The binary compound of hydrogen and sulfur H₂S₈
octasulfate noun: Any compound that has eight sulfate groups or ions
octasulfide noun: Any sulfide containing eight atoms of sulfur.
octasulfur noun: The most common allotrope of sulfur (S₈), containing eight atoms in a ring.
octasulphate noun: Alternative form of octasulfate.
octasulphide noun: Alternative spelling of octasulfide.
octasyllabic adjective, noun: Alternative form of octosyllabic.
octateuch noun /ˈɒktətjuːk/: A collection of eight books; especially, the first eight books of the Old Testament.
octathlete noun: Competitor in an octathlon.
octathlon noun /ɒkˈtæθlɒn/: A sporting event consisting of eight different sports or contests.
octatomic adjective: Having eight atoms in each molecule
octatonic adjective: Containing eight notes.
octatonic scale noun: A scale that has four half step intervals and four whole step intervals that alternate.
octatriacontane noun: The aliphatic saturated hydrocarbon having 38 carbon atoms, C₃₈H₇₈
octatriacontanoic adjective: Of or pertaining to octatriacontanoic acid or its derivatives
octatriacontanoic acid noun: A long-chain saturated fatty acid having 38 carbon atoms
octatriene noun: Any of several isomeric trienes having eight carbon atoms
octatropine noun: A muscarinic antagonist and antispasmodic, used in the methylbromide form.
octaval adjective /ɒkˈteɪvəl/: Of, pertaining to, or relating to an octave.
octavalence noun: The property of being octavalent.
octavalency noun: The condition of being octavalent
octavalent adjective: Having an atomic valence of 8.
octavate noun, verb /ˈɒktəveɪt/: To resonate or sound one octave higher or lower.
octavated adjective: Altered to sound a pitch one octave lower than its usual range.
octavating adjective: Transposed by an octave.
octavation noun /ˈɒktəveɪʃən/: Transposition by an octave.
octave adjective, noun, verb /ˈɒktɪv/: An interval of twelve semitones spanning eight degrees of the diatonic scale, representing a doubling or halving in pitch frequency.
octave clef noun: a symbol showing that the pitch of a note is to be raised by one or two octaves.
Octave Day of Easter noun: Synonym of Quasimodo (“the Sunday one week after Easter Sunday”).
octave flute noun: A flute that is smaller than a Western concert flute and pitched nearly an octave higher.
Octave of Easter noun: The eight-day period of holy days that begins with Easter Sunday (inclusive thereof).
octave species noun: In Ancient Greek music, a specific sequence of intervals within an octave.
octaved adjective: Having a specified kind or number of octaves.
Octavia proper noun /əkˈteɪ.vi.ə/: A female given name from Latin, in quiet use since the Middle Ages.
Octavian proper noun /ɒkˈteɪvi.ən/: A male given name from Latin, notably borne by Augustus (Caesar) between 44 and 27 BCE
octaviate verb: To octavate.
octaviation noun: The repetition of a chord an octave higher or lower than the original.
octavic adjective: Synonym of octic.
octavin noun: A single-reed instrument with a conical bore, originating in Germany.
octavina noun: A stringed musical instrument resembling the guitar.
octaving noun: An audio effect in which a signal is combined with another version of itself that is an octave higher or lower.
octavius noun: Alternative form of octarius (the pint (eighth of a gallon) in the apothecaries' system)
octavo noun: A sheet of paper 7 to 10 inches (= 17.78 to 25.4 cm) high and 4.5 to 6 inches (= 11.43 to 15.24 cm) wide, the size varying with the large original sheet...
octavofinal noun: A match or game between two of the last sixteen competitors in a given tournament or sporting competition.
octavolateral adjective: octaval and lateral: Used exclusively to describe a structure in the brains of fishes, namely the medial octavolateral nucleus or the dorsal octavolateral...
octenal noun: Any of several isomeric unsaturated aliphatic aldehydes having eight carbon atoms and one double bond.
octenary noun: Octal; base eight.
octene noun /ˈɒktiːn/: Any of many isomeric alkenes having eight carbon atoms and one double bond; some of them are used in the manufacture of polymers
octenidine noun: The imino pyridine derivative N-octyl-1-[10-(4-octyliminopyridin-1-yl)decyl]pyridin-4-imine
octenidine dihydrochloride noun: A cationic surfactant.
octennial adjective: Occurring every eight years.
octennially adverb: Every eight years.
octennium noun: An eight-year period.
octenol noun: 1-octen-3-ol, a chemical in human breath and sweat that attracts biting insects such as mosquitoes.
octenyl noun: Any of several isomeric radicals derived from an octene
octeract noun: An eight-dimensional hypercube
octet noun /ɒkˈtɛt/: A group or set of eight of something.
octet rule noun: A rule stating that atoms lose, gain, or share electrons in order to have a full valence shell of 8 electrons. (Hydrogen is excluded because it can hold a...
octethyl noun: Alternative form of octaethyl.
octetonium noun: A color singlet bound state of color-octet scalars.
octett noun: Alternative spelling of octet.
octette noun: Rare spelling of octet.
OCTG noun: Abbreviation of Oil Country Tubular Goods. Tubing, casing and drill pipes manufactured according to API Specification 5CT.
octhilinone noun: A particular fungicide.
octiamond noun: A polyiamond made up of eight triangles.
octic adjective, noun /ˈɒktɪk/: Of the eighth degree or order.
octile noun: Any of the quantiles that divide an ordered sample population into eight equally numerous subsets.
octilinear adjective: Composed of horizontal, vertical and/or diagonal (45 degrees) line segments only
octillion number /ɒkˈtɪl.iː.ən/: A thousand trillion trillion, a billion billion billion: 1 followed by 27 zeros, 10²⁷.
octillionaire noun: Somebody whose wealth is at least one octillion (10²⁷) currency units.
octillionfold adjective, adverb: By a multiple of one octillion; by an octillion times as much or as many.
octillionth adjective, noun: The ordinal form of the number octillion.
octinoxate noun: The ester octyl methoxycinnamate when used as a sunscreen.
octinucleate adjective: Alternative form of octanucleate.
octisalate noun: The ester octyl salicylate when used as a sunscreen.
octitol noun: Any sugar alcohol having eight carbon atoms
octium noun: The element oxygen.
octlet noun: A word (or rather, a doubleword) consisting of eight bytes (64 bits)
octli noun: Pulque.
octo noun, prefix: An octopus (safety device).
octo-champ noun: Alternative spelling of octochamp.
octoad noun: Synonym of ogdoad (“a thing made up of eight parts”).
octoalloy noun: An alloy of eight metals (gold, silver, copper, lead, zinc, tin, iron, and antimony or mercury), formerly used in India for making idols.
octoate noun: octanoate
octobass noun: A very large bass requiring two musicians, one to finger and one to bow.
octobassist noun: Someone who plays the octobass.
October proper noun, noun, verb /ɒkˈtəʊ.bə/: The tenth month of the Gregorian calendar, following September and preceding November.
October 8 Jew noun: Alternative form of October 8th Jew
October 8th Jew noun: A Jewish person who reconnected with their Jewish identity as a result of the Hamas-led attack on Israel on October 7, 2023.
October beer noun: A strong ale traditionally brewed in October.
October effect noun: A market anomaly caused by widespread psychological anticipation of stock market crashes in the month of October.
October surprise noun: An occurrence that unexpectedly comes to public attention just prior to a November election, especially a presidential election, and that is likely to...
Octoberfest proper noun: The Bavarian holiday (Oktoberfest or Wiesn), or any such holiday, celebrated in late September to early October, typically featuring German music, cuisine,...
Octobering noun: A naming ceremony in the early Soviet Union meant to serve as an irreligious and Marxist alternative to christening.
Octoberish adjective: Resembling or characteristic of the month of October.
Octoberist noun: Alternative form of Octobrist.
Octoberly adjective: Characteristic of the month of October.
Octobery adjective: characteristic of the month of October
octobrachiate adjective: Having eight brachia, arms, or rays.
Octobral adjective: Characteristic of October
Octobrist noun: A member of the league formed October 1905 in response to imperial policies.
octocellular adjective: Having eight cells.
octocentenary noun: An eight-hundredth anniversary.
octocentennial adjective, noun: Relating to an octocentenary
octochaetid adjective, noun: Belonging or related to the family Octochaetidae of earthworms.
octochamp noun /ˈɒktəʊˌt͡ʃamp/: A winner of eight consecutive heats of the British television game show Countdown.
octochord noun: Alternative form of octachord.
octoclothepin noun: Synonym of clorotepine.
octocog alfa noun: A recombinant form of factor VIII, an essential blood-clotting protein.
octocontrabass noun: An instrument that is pitched one octave below the contrabass.
octocopter noun: An unmanned rotorcraft having eight rotors.
octocoral noun: An anthozoan of the subclass Alcyonaria, having eight-branched tentacles and eight septa.
octocorallian noun: Any coral of the subclass Octocorallia
octocoralline adjective: Of or relating to the octocorals.
octocore adjective: Composed of eight cores.
octocrylene noun: An ester formed by the condensation of a diphenylcyanoacrylate with 2-ethylhexanol, used in sunscreens and cosmetics.
octodactylous adjective: Having eight fingers.
octode noun /ˈɒk.təʊd/: A thermionic valve that has eight electrodes or similar elements
octodecillion number /ˌɒktoʊdəˈsɪl.i.ən/: 10⁵⁷.
octodecimal adjective: Having eight times ten faces.
octodecimo noun: A size of a sheet of paper resulting from folding and cutting a sheet of paper into eighteenths (3.5"–4.5" x 4.9"–5.9").

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0): each word's first meaning. A word with a page of its own links to it; for the rest, this line is PlainSpell's entry. Total under O: 20,049 words, in 67 parts.