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| hafnium |
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noun
- a metallic chemical element (symbol Hf) with an atomic number of 72.
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| hahnium |
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noun
- original name of the transuranic element dubnium
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| halide |
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noun
- (chemistry) A salt of any halogen acid.
- Potassium iodide is a .
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| halocarbon |
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noun - (chemistry) any compound formally derived from a hydrocarbon by replacing at least one hydrogen atom with a halogen, but especially by replacing all hydrogen atoms with halogen(s)
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| halogen |
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noun
- (chemistry) Any element of group 7, i.e. fluorine, chlorine, bromine, iodine and astatine, which form a salt by direct union with a metal.
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| halogenate |
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verb (halogenates, halogenating, halogenated, halogenated)
- (context, chemistry, transitive) To treat with, or react with, a halogen or a hydrohalic acid.
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| hard |
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adjective
- Resistant to pressure.
- Requiring a lot of effort to do or understand
- a hard problem
- Demanding a lot of effort to endure.
- a hard life
- (context, of a person) , severe, harsh, unfriendly, brutal.
- Unquestionable.
- hard evidence
- Of drink, strong.
- Of water, high in dissolved calcium compounds.
- (context, slang, vulgar) Sexually aroused.
- (bodybuilding) Having muscles that are tightened as a result of intense, regular exercise.
adverb (harder, hardest)
- With much strength or energy
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| hardness |
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noun
- The quality of being hard.
- An instance of this quality; hardship.
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| hard water |
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noun
- (chemistry) water with a high concentration of dissolved minerals, especially calcium, making it difficult to lather with soap
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| HDPE |
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initialism - High Density Polyethylene
category:Initialisms
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| HE |
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abbreviation
- His Excellency, Her Excellency
- His Eminence
- high explosive
- Higher Education
- Health Education
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| heavy |
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noun (pl2=heavies)
- A villain or bad guy; the one responsible for evil or aggressive acts.
- With his wrinkled, uneven face, the actor always seemed to play the in films.
- (slang) A doorman, bouncer
- A fight started outside the bar then the heavies came out and stopped it.
adjective (heavier, heaviest)
- (context, of a physical object) Having great weight.
- (context, of a topic) serious, Serious, somber.
- (context, UK, slang) Good.
- This film is .
- (context, of a rate of flow) high, High, great.
- (context, UK, slang) Armed.
- Come , or not at all.
- (context, Music terminology) louder, more distorted
- ''Metal is heavier than swing.
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| heavy hydrogen |
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noun (uncountable)
- Another name for deuterium.
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| helium |
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noun
- A colorless and inert gas, and the second lightest chemical element (symbol He) with an atomic number of 2 and atomic weight of 4.002602.
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| hemiacetal |
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noun - (chemistry) any of a class of compounds of general formula R2C(OH)OR' (where R' is not H)
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| hemicellulose |
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noun - (chemistry) a mixture of several plant polysaccharides, of smaller molecular weight than cellulose, that are soluble in dilute alkali; they are involved in the manufacture of paper, and are used in the production of furfural and ethanol
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| heptad |
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noun
- a group of seven things
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| heptane |
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noun
- (organic compound) Any of the nine isomers of the saturated aliphatic hydrocarbon C7H16, obtained from petroleum, especially n-heptane (CH3(CH2)5CH3)
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| hetero |
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noun
- (informal) A heterosexual person.
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| heteroaromatic |
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adjective - (chemistry) having the characteristics of an aromatic compound whilst having at least one non-carbon atom in the ring
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| heteroatom |
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noun - (chemistry) any atom in a heterocyclic ring (or other structure normally built of carbon atoms) that is not a carbon atom
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| heterocyclic |
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adjective
- (organic chemistry) Of a cyclic compound that contains one or more atoms other than carbon in at least one of its rings.
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| heterogeneous |
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adjective
- diverse, Diverse in kind or nature; composed of diverse parts.
- (mathematics) incommensurable, Incommensurable because of different kinds.
- (physics): Having more than one phase (solid, liquid, gas) present in a system or process.
- (chemistry): Visibly consisting of different components.
- (information technology): A network comprising different types of computers, potentially with vastly differing memory sizes, processing power and even basic underlying architecture. Alternatively, a data resource with multiple types of formats.
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| heteropolar |
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adjective - Of an electric generator that produces alternating current
- (chemistry) Formed by ions of opposite charge
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| hexabasic |
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adjective - (chemistry) (of an acid) containing six replaceable hydrogen atoms
- (chemistry) (of a salt) having six atoms of a univalent metal
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| hexafluoride |
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noun - (chemistry) any fluoride containing six fluorine atoms in each molecule
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| hexane |
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noun
- (organic compound) Any of five isomeric aliphatic hydrocarbons, C6H14. They are colorless, volatile liquids.
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| hexavalent |
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adjective - (chemistry) having a valence of 6
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| hexose |
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noun
- (carbohydrate) A sugar or saccharide containing six carbon atoms.
- Glucose is a common
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| hf |
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abbreviation
- (Internet) have fun
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| ho |
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noun (hoes)
- (context, pejorative, slang) A woman who engages in prostitution.
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| holmium |
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noun
- a metallic chemical element (symbol Ho) with an atomic number of 67.
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| homocyclic |
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adjective - (chemistry) describing a cyclic system in which all the atoms of the ring are of the same element
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| homologous |
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adjective
- Showing a degree of correspondence or similarity such that it suggests a common origin.
- (biology) corresponding to a similar structure in another life form with a common evolutionary origin e.g. flippers and hands
- (chemistry) belonging to a series of aliphatic organic compounds that differ only by the addition of a CH2 group
- (genetics) having the same morphology as another chromosome
- homologous blood donation
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| hydracid |
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noun - (chemistry) An acid that does not contain any oxygen as opposed to an oxyacid; they are all binary compounds of hydrogen and a halogen or pseudohalogen.
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| hydrargyrum |
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noun
- (chemistry) (medicine) The element mercury.
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| hydrate |
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noun
- (chemistry) A solid compound containing or linked to water molecules.
- (context, inorganic compound, rare) water, Water.
verb (hydrat, ing)
- (transitive) To take up, consume or become linked to water.
- A lotion can the skin.
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| hydrated |
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adjective
- (chemistry) Chemical combinated with water, H2O, in its molecular form.
- We took the powdered milk and it until it was drinkable.
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| hydrazine |
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noun
- (context, inorganic compound, uncountable) A corrosive, fuming liquid, NH2-NH2, used as a rocket fuel.
- (context, organic chemistry, countable) Any member of the class of organic compounds formally derived from it.
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| hydrazone |
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noun - (chemistry) any compound, of general formula R2C=NNR2, formally derived from an aldehyde or ketone by replacing the carbonyl group with =NNH2 or derivative
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| hydric |
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adjective - Characterized by, or requiring moisture
- (chemistry) Of, or relating to hydrogen
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| hydride |
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noun - (chemistry) a compound of hydrogen with a more electropositive element
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| hydriodic acid |
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noun - (chemistry) a solution of hydrogen iodide, HI, in water; it is a strong acid and reducing agent
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| hydrobromic |
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adjective - (chemistry) Composed of hydrogen and bromine
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| hydrobromic acid |
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noun
- (inorganic compound) A solution of hydrogen bromide, HBr, in water; it is a strong acid, used in the production of bromine compounds.
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| hydrocarbon |
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noun
- (organic chemistry) A compound consisting primarily of carbon and hydrogen atoms.
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| hydrochloric |
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adjective - (chemistry) Of or relating to hydrochloric acid.
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| hydrochloric acid |
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noun
- (chemical compound) A strong acid made by dissolving the gas, hydrogen chloride, in water. It reacts with alkalis, bases and many metals to form chlorides; it has many industrial applications'
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| hydrochloride |
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noun - (chemistry) A compound of hydrochloric acid with an organic base such as an amine
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| hydrocyanic acid |
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noun (or prussic acid)
- (chemistry) a solution of hydrogen cyanide, HCN, in water; a weak poisonous acid, used as a fumigant
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| hydrodesulfurization |
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noun - (chemistry) a process for lowering the sulfur content of petroleum and similar products by catalytic hydrogenation, sulfur compounds being converted to hydrogen sulfide
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| hydrofluoric |
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adjective - (chemistry) Containing hydrogen and fluorine.
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| hydrofluoric acid |
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noun
- (chemistry) A solution of hydrogen fluoride, HF, in water; it is a weak but very corrosive acid, used in the production of fluorine compounds, and in metallurgy.
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| hydroformylation |
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noun - (chemistry) the reaction of an olefin with carbon monoxide and hydrogen to form an aldehyde
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| hydrogen |
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noun
- The lightest chemical element (symbol H) with an atomic number of 1 and atomic weight of 1.00794.
- Molecular hydrogen (H2), a colourless, odourless and flammable gas at room temperature.
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| hydrogen bond |
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noun
- (chemistry) a weak bond in which a hydrogen atom in one molecule is attracted to an electronegative atom (usually nitrogen or oxygen) in the same or different molecule
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| hydrogen bromide |
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noun
- (inorganic compound) A colourless gas having an irritating smell; it has the molecular formula HBr, and dissolves in water to form hydrobromic acid; it has many industrial applications including the production of barbiturates and synthetic hormones.
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| hydrogen chloride |
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noun
- (inorganic compound) An inorganic compound with the formula HCl. Forms hydrochloric acid when dissolved in water.
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| hydrogen cyanide |
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noun
- (chemistry) A colourless, very poisonous, volatile liquid, HCN, used in the production of dyes, plastics and fumigants; it dissolves in water to form hydrocyanic acid and reacts with bases to form cyanides, and with some organic compounds to form nitriles.
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| hydrogen fluoride |
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noun - (chemistry) a colourless fuming liquid or gas, having a molecular formula of HF; it dissolves in water to form hydrofluoric acid and has many industrial uses including the production of teflon and the refining of uranium; it corrodes skin, flesh and bone, and any skin contact must be avoided
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| hydrogen iodide |
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noun - (chemistry) a colourless gas with molecular formula HI, having a suffocating smell; it forms hydriodic acid when dissolved in water
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| hydrogen ion |
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noun - (chemistry) a proton combined with one or more water molecules; usually written H3O+ and called the hydronium ion though is best considered as H9O4+ but is often written H+(aq) for simplicity
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| hydrogenolysis |
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noun - (chemistry) the cleavage of a molecule, especially that of a carbon-carbon bond, with the addition of hydrogen atoms to the fragments
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| hydrogenous |
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adjective
- of, related to, or containing hydrogen
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| hydrogen peroxide |
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noun
- (chemical compound) A colourless liquid, H2O2, soluble in water, used as a mild antiseptic, bleaching agent (especially for bleaching hair), oxidizing agent and chemical reagent.
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| hydrogen sulfide |
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noun
- (chemical compound) A toxic gas, H2S, smelling like rotten eggs and used in analytical chemistry and industry.
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| hydrolysis |
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noun - a chemical process of decomposition involving the splitting of a bond and the addition of the hydrogen cation and the hydroxide anion of water
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| hydrolyze |
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verb (hydrolyz, ing) (transitive and intransitive)
- (chemistry) to undergo, or to subject something to hydrolysis
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| hydroperoxide |
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noun - (chemistry) any mono-substituted derivative of hydrogen peroxide - ROOH
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| hydrophilic |
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adjective - (physics),(chemistry) having an affinity for water; able to absorb, or be wetted by water
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| hydrophobic |
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adjective - (physics),(chemistry) lacking an affinity for water; unable to absorb, or be wetted by water
- of, or having hydrophobia (rabies)
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| hydroquinone |
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noun
- (organic compound) The diphenol para-dihydroxy benzene, used as a mild reducing agent in photographic developing; isomeric with catechol and resorcinol.
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| hydrosulfide |
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noun - (chemistry) any compound formally derived from hydrogen sulfide by replacing one hydrogen atom with a metal or other radical; a thiol or mercaptan
- (chemistry) the HS- anion
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| hydrosulfite |
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noun - (chemistry) dithionite
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| hydrous |
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adjective
- (chemistry) containing combined water; hydrated
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| hydroxide |
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noun - (chemistry) An univalent anion (OH-1) based on the hydroxyl functional group.
- Any substance containing such an anion.
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| hydroxy acid |
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noun - (chemistry) a carboxylic acid that also contains a hydroxy group
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| hydroxyl |
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noun
- (chemistry) A univalent radical or functional group, (-OH), in organic chemistry; present in alcohols, phenols, carboxylic acids and certain other classes of compounds
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| hydroxylamine |
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noun
- (inorganic compound) An explosive inorganic derivative of ammonia, NH2OH, used as a reducing agent, and in organic synthesis.
- (organic chemistry) Any organic derivative of this compound.
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| hypergolic |
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adjective
- of fuel or propellant, igniting spontaneously on contact with an oxidiser
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| hypertonic |
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adjective
- (context, of a solution) having a greater osmotic pressure than another
- (anatomy) having a very high muscular tension; spastic
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| hypo |
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noun
- (photography) sodium thiosulfate, a photographic fixing agent.
- (slang) A hypoglycaemia attack in a person with diabetes.
- (slang) The substance sodium hyposulfite.
- (slang) A hypodermic syringe .
- (slang) hypothecation, Hypothecation.
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| hypochlorite |
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noun - (chemistry) any salt of hypochlorous acid; used as a household bleach
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| hypochlorous |
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adjective - (chemistry) Pertaining to or derived from chlorine having a valence lower than in chlorous compounds.
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| hypochlorous acid |
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noun - (chemistry) a weak, unstable acid, HOCl, known only in solution; it is made by the action of chlorine on water and, along with its salts, the hypochlorites, is used as a household bleach
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| hypophosphite |
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noun - (chemistry) any salt of hypophosphorous acid
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| hypophosphorous acid |
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noun '''hypophosphorous acid
- (chemistry) a pale yellow liquid, H3PO2, used as a reducing agent
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| hyposulfurous acid |
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noun (or hyposulphurous acid, previously known as hydrosulfurous acid or hydrosulphurous acid)
- (chemistry) an unstable acid, H2S2O4, only known in solution, used as a reducing agent; its salts are hydrosulfites (or hyposulfites)
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