Definition of chemical in English:



  • 1Relating to chemistry, or the interactions of substances as studied in chemistry.

    ‘the chemical composition of the atmosphere’
    • ‘When a galaxy is bright enough that its starlight can be seen directly, we can use spectroscopy to discern its chemical composition and are able to relate it to nearby galaxies around us today.’
    • ‘Typical photopolymers use a single chemical process for bonding molecules together both to form the medium and perform the recording.’
    • ‘These left-over electrons are the ones farthest from the nucleus and because of this they will determine the chemical interactions of the atom with other atoms.’
    • ‘The chemical composition of the air is not a precondition for life but the result of it.’
    • ‘Now, let us examine the chemical composition of lipids.’
    • ‘Elements are materials that cannot be reduced to simpler substances by normal chemical means.’
    • ‘It may also be in part caused by vigorous chemical interaction between the silicate mantle and the iron core.’
    • ‘This resistance to chemical oxidation is likewise due to the resonance stability of the benzene.’
    • ‘The number of solute particles which form in a solution depends on the chemical nature of the solute.’
    • ‘Explosives are substances that produce violent chemical or nuclear reactions.’
    • ‘The third atom can detach from the ozone molecule and reattach to molecules of other substances, changing their chemical composition.’
    • ‘These resonant frequencies depend on the chemical composition of the substance: which atoms it contains and how they are joined together.’
    • ‘This new measurement technique will allow scientists to detect the chemical composition of the Martian atmosphere, ionosphere, and surface.’
    • ‘Scientists have long used ultra-fine glass tubes known as capillaries to analyze the chemical makeup of substances.’
    • ‘The differences in the chemical composition of the two give hints about how Chinese brewing may have evolved.’
    • ‘In fairness, any radiation that can ionize an atom can affect chemical changes in a substance.’
    • ‘Many of them are enzymes, molecules that catalyse processes of chemical change.’
    • ‘The bilayer is not a homogeneous film, but its chemical composition and molecular structure distinctly varies along the membrane normal.’
    • ‘That kind of resolution allows exquisitely exact areas to be analyzed for chemical composition.’
    • ‘In its simplest terms, a chemical standard is a substance for which the exact composition is known.’
    technological, technical
    View synonyms
    1. 1.1 Relating to chemicals.
      ‘chemical treatments for killing fungi’
      • ‘The hormone treatment is straightforward chemical castration - I am now impotent but it's an advantageous trade-off against a possibly fatal alternative.’
      • ‘Lipids belong to a larger class of chemical substances: esters.’
      • ‘They'd proposed a system of shed inspections and post-harvest chemical treatment, to ensure the disease couldn't spread interstate.’
      • ‘These are chemical substances that when added to the analyte, change color at the equivalence point.’
      • ‘This new laser treatment may replace deep chemical peels and laser skin resurfacing, which often leave the skin raw and take more than a week to heal.’
      • ‘Motives for merger, acquisition and divestiture activity in the water treatment chemical industry are varied.’
      • ‘Why would a chemical substance as seemingly innocuous as milk sugar cause a body misery?’
      • ‘If you have relaxed hair (as explained below in the chemical treatments section), it is best to use a natural bristle brush.’
      • ‘These days, Grace is working to undo the damage done by the sun's harsh rays, treatments involving microdermabrasion and chemical peels.’
      • ‘Water treatment chemical suppliers are becoming more global, especially European ones who moved into the United States.’
      • ‘First, DDT, like most chemical substances, is reasonably safe when used responsibly, and harmful when used indiscriminately.’
      • ‘Practical control of premature sprouting in storage is achieved through the use of low temperatures or treatment with chemical sprout suppressants.’
      • ‘For faster fading, your dermatologist may prescribe a stronger lightener, chemical peel, laser treatment or even a combination of the three.’
      • ‘Councillors have been told that fitting water filtering and chemical treatment would cost £223,000 plus annual running costs of £45,220.’
      • ‘Just as the sweet smells of fall fill the air, the residents of the housing complex where I live are notified again - for the fourth time this year - of a chemical lawn treatment.’
      • ‘He appears to be motivated to confront his problems and is willing to participate in all forms of recommended treatment, including chemical castration.’
      • ‘The water treatment chemical industry in the United States is still not concentrated, but it has undergone definite consolidation in the past two decades.’
      • ‘The fragile reinforced concrete elements were repaired and protected through new chemical treatments.’
      • ‘When we consider chemical substances most can exist in any of the three states.’
      • ‘Treatment methods can be chemical or ablative.’
    2. 1.2 Relating to or denoting the use of poison gas or other chemicals as weapons of war.
      • ‘Unlike biological and chemical weapons, however, they affect humans indirectly rather than directly.’
      • ‘Even the use of chemical or biological weapons is problematic.’
      • ‘The north has responded with mysterious plans using thousands of commandos and chemical weapons.’
      • ‘Aside from the nuclear variety of WMD, biological and chemical weapons pose serious dangers.’
      • ‘And for the record I do think he had WMD - chemical weapons in particular.’
      • ‘The specter of biological or chemical weapons being used in terrorist attacks substantially raises the possibility of widespread human and social destruction.’
      • ‘The war that followed saw them employing chemical weapons and both sides firing ballistic missiles at major cities.’
      • ‘We know that he's rushing hard to try to get a nuclear capability, that he is building biological and chemical weapons and has missiles with which to deliver those.’
      • ‘The next adversary may use chemical weapons or pull its main forces into urban areas to fight to the bitter end.’
      • ‘Fear grows when Harry begins showing signs of nerve gas poisoning, suggesting a chemical weapon attack’
      • ‘They have every incentive to cooperate with us because these are people who are promising to, you know, detonate dirty bombs or chemical weapons and the like in Europe.’
      • ‘Nuclear and chemical weapons are definitely human products.’
      • ‘It has been alleged in the course of the raids that chemical weapons and napalm bombs were also used.’
      • ‘In previous wars it took large artillery bombardments to make chemical weapons effective.’
      • ‘What's your take on the effectiveness of bio and chemical terror weapons?’
      • ‘Wait, they're going to poison us with chemical weapons!’
      • ‘They have not sold anyone chemical weapons, as far as anyone knows.’
      • ‘Never develop, produce, acquire, stockpile, transfer, or retain chemical weapons or help anyone to do so.’
      • ‘It is possible that the leader gave orders to torch oil wells, launch chemical weapons or fire missiles, but that the commands were ignored, he added.’
      • ‘He has had chemical weapons and he's used them.’


  • 1A distinct compound or substance, especially one which has been artificially prepared or purified.

    ‘never mix disinfectant with other chemicals’
    • ‘It is an organic chemical produced by reacting chlorine gas with phenol.’
    • ‘Toxic chemicals such as benzene, toluene and methyl benzene were included in the list.’
    • ‘Breakfast cereals and breads also contain substantial quantities of the chemical.’
    • ‘Alcohol contains ethanol, a chemical that causes blood vessels to expand, which can give you a headache.’
    • ‘It stores and processes hundreds of tonnes of toxic and highly inflammable chemicals and compounds.’
    • ‘Every pit or track contains a certain chemical that reacts to protein matrices.’
    • ‘Once in place, it expects chemical companies to volunteer to test specific chemicals.’
    • ‘The other chemical is an estrogen-like compound in women's urine.’
    • ‘Any scientist, organization, or member of the public may nominate a chemical for NTP testing.’
    • ‘There is often more than one synthetic route for preparing a desired chemical.’
    • ‘Benzene, a chemical in detergents and oven cleaners, is also known to be a carcinogen.’
    • ‘If the burning chemical is a powder-like substance such as lime, brush it off the skin before flushing.’
    • ‘Each year, there is more sulfuric acid produced in the United States than any other chemical.’
    • ‘However, aquatic life is much more sensitive to even these low levels of toxic chemicals, Pardue says.’
    • ‘Quite apart from this, artificial fluoride is a toxic chemical which we neither need nor want in our public water supplies.’
    • ‘A battery is basically a simple electrochemical device to store electrical energy as chemicals.’
    • ‘Also, the chemical plant was processing ammonium nitrate, a stable chemical that requires a substantial infusion of energy to explode.’
    • ‘Tannic acid, or tannin, is the same chemical used in tanning animal hides.’
    • ‘Chlorine is a basic industrial chemical, prepared in immense quantities by electrolysis of brine.’
    • ‘If the other chemical was using those electrons to hold it together, it would fall apart.’
    1. 1.1 An addictive drug.
      as modifier ‘chemical dependency’
      • ‘Nicotine, the active chemical, is a natural pesticide and some farmers use an infusion of tobacco to protect their trees from insects.’
      • ‘Addiction is not simply a matter of introducing a chemical into someone's body, even if it is done often enough to create tolerance and withdrawal symptoms.’
      • ‘Scientists continue to explore the remarkable protective effect of nicotine - the addictive chemical in tobacco - on the brain.’
      • ‘Greenpeace is compiling a list of products which contain chemicals regarded as being the most dangerous.’
      • ‘No, hemp fabric does not contain the narcotic chemical that, when smoked produces the ‘high’ that smoking marijuana produces.’
      • ‘This suggests to him that dopamine, a major chemical behind addictive behavior, may be present as well.’
      • ‘The receptors are also sensitive to the compound THC, the primary psychoactive chemical in marijuana.’
      • ‘It is normally protected from chemicals and drugs by the blood-brain barrier, which acts as a filter.’
      • ‘What is really cool is that the lemurs also become intoxicated by the narcotic effects of the chemicals.’
      • ‘Researchers on both sides of the Atlantic are in a race to produce a drug that targets the effects of nicotine - the chemical which leads to tobacco addiction.’
      • ‘As with all chemicals, the hazard depends mainly upon the amount taken into the body.’
      • ‘He says he has been clean from heroin for years and now takes a prescribed opiate to combat the pain, but is desperate to get off the addictive chemical.’
      • ‘It is essentially a chemical that works exactly like an amphetamine without actually being one.’
      • ‘She wasn't on drugs or drink, there was no chemical altering her behaviour.’
      • ‘Some tribes have incorporated culture and spirituality in the healing process in hopes that the addict can beat the highly addictive chemical.’
      • ‘Few scientific challenges are more complex than understanding the health risks of a chemical or drug.’
      • ‘So while these two chemicals are dangerous to most of us, they are impossible to ban.’
      • ‘It was filled with dangerous chemicals such as tar and nicotine, which were proven to be bad for the health.’


Late 16th century: from French chimique or modern Latin chimicus, chymicus, from medieval Latin alchymicus, from alchimia (see alchemy).