Definition of radical in English:



  • 1(especially of change or action) relating to or affecting the fundamental nature of something; far-reaching or thorough.

    ‘a radical overhaul of the existing regulatory framework’
    • ‘The essential elements of power remained the same without a radical shift in strategy or force structure.’
    • ‘It could be many years before the conditions are such that a radical reform of Social Security is possible.’
    • ‘The rest of the time, they assumed that economic rationalism implies support for radical free-market reform.’
    • ‘‘This marks a radical change in the paradigm for selling time on television networks,’ he says.’
    • ‘Des Ball says the Intelligence system needs radical overhaul.’
    • ‘Meanwhile, dams associated with hydroelectric plants can cause radical disruption of area ecosystems.’
    • ‘Yet not a single political party is uncompromisingly committed to the sort of programme of radical reform which would rectify these horrific wrongs.’
    • ‘There have been radical changes in the regulation of air travel, from a newly federalized security system to tighter restrictions on what items can be brought onto a plane.’
    • ‘The reason for this kind of fear-mongering is obvious: it's a way to gin up support for radical reforms.’
    • ‘Efforts to improve air quality in York are not radical enough to make a real difference, councillors have claimed.’
    • ‘Thailand combined the introduction of universal access to subsidised health care with a radical shift in funding away from urban hospitals to primary care.’
    • ‘Are the arguments of those who predict a radical change in the nature of 21st century wars that groundless after all?’
    • ‘Fourth, the tax system needs radical reform.’
    • ‘As a result of these classes, Emmy made the radical decision to abandon school teaching and make a career as a mathematician.’
    • ‘This will undergo a radical change, with an extension to the northbound M606 and a new routing system around it.’
    • ‘Both groups would be affected by a radical change in the business climate.’
    • ‘The people are exhausted from the radical changes that affect their way of life.’
    • ‘The proposal makes sweeping, radical changes in the law, but the regulatory analysis does not reflect them.’
    • ‘‘The question,’ he added, ‘is whether the Executive is actually up for radical change?’’
    • ‘But even here, the radical change began with federal courts taking major areas of public policy away from state legislatures.’
    thoroughgoing, thorough, complete, total, entire, absolute, utter, comprehensive, exhaustive, root-and-branch, sweeping, far-reaching, wide-ranging, extensive, profound, drastic, severe, serious, major, desperate, stringent, violent, forceful, rigorous, draconian
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    1. 1.1Forming an inherent or fundamental part of the nature of someone or something.
      ‘the assumption of radical differences between the mental attributes of literate and non-literate peoples’
      • ‘He said yesterday: ‘Football results do not make a radical difference to society but they can have an impact.’’
      • ‘There's a radical difference between this kind of traditionalist politics and laissez-faire conservative politics.’
      • ‘Since independence, an emergent class structure has become apparent in urban sectors with radical differences in wealth between the rich and poor.’
      • ‘To that end, you'll notice a radical difference in speed and handling depending on the size of the car.’
      • ‘We want to make a radical difference to the prospects and perception of the town.’
      • ‘The following is a marvellous, energizing, healing ceremony that really does make a radical and lasting, difference in your life.’
      • ‘Only those who do not understand the radical difference between the movement of socialist women and bourgeois suffragettes can think this way.’
      • ‘As for the property rights of authors to their works, the consequences of these differences are radical.’
      • ‘These radical differences reveal crucial changes in American culture.’
      • ‘The radical injustice of early capitalism gave birth to the overcompensation of totalitarian communism.’
      • ‘But then again, a subtle difference was preferable to a radical one, and it did give me a short-term confidence boost.’
      • ‘Note also the radical difference between how our culture defines ‘fashionable’ thinness for men and women.’
      • ‘Iceland displays some radical cultural differences with its temporary American inhabitants.’
      • ‘Here, and elsewhere in the installation, one radical difference between the classical and modern sculptures was made evident.’
      • ‘The story also illustrates the most radical difference between mania and hypomania.’
      • ‘It should be easy enough to guess the reason for this radical difference in behaviour.’
      • ‘The difference between then and now was so radical he was at loss about what to think.’
      • ‘This is the first time we have encountered such radical differences within one lot.’
      • ‘For translators, the radical differences between Chinese and English are a source of despair and opportunity.’
      • ‘The chapter demonstrates that fantasies and day dreams may have radical differences in both structure and content, depending on the use to which we put them.’
      fundamental, basic, essential, quintessential
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    2. 1.2(of surgery or medical treatment) thorough and intended to be completely curative.
      • ‘By the seventeenth century, more radical treatments, often chemical, came into fashion and the gentle, gradual, and individualized diet fell out of favour.’
      • ‘The same diagnostic delay led to 64 patients having more radical treatment than necessary.’
      • ‘Men could then be offered radical surgery if their test results showed a worsening trend.’
      • ‘The patient underwent preoperative chemotherapy and subsequent radical hysterectomy and bilateral pelvic lymphadenectomy.’
      • ‘For these women the recommended treatment is often modified radical mastectomy.’
      • ‘Urinary incontinence is very common, but most people do not desire or require radical treatment.’
      • ‘The patient in this case study underwent ablative surgery consisting of a radical hemipelvectomy carried out by an orthopaedic oncologist.’
      • ‘Despite this risk, radical surgery is not indicated for the treatment of this lesion.’
      • ‘Each of the main treatments radical prostatectomy, radiation therapy, and monitoring has risks.’
      • ‘The principal concern is that age bias will lead to the use of palliative therapies as opposed to curative treatments and radical surgical procedures in older adult patients.’
      • ‘Delayed recognition of cancer as a result of inaccuracy or inefficiency may also lead to increases in distress and disability for the patient, in addition to the eventual need for more radical treatment.’
      • ‘More serious cancers, however, will require radical surgery, radiotherapy, and chemotherapy.’
      • ‘A radiographic evaluation is not indicated unless radical treatment is being contemplated.’
      • ‘In patients who are unfit to have radical surgery, radiotherapy may be administered to the inguinal lymph nodes.’
      • ‘Last week, one simple health message dominated the US media: radical prostate surgery for prostate cancer saves lives.’
      • ‘Such patterns of care should increase the frequency with which patients are offered treatments that alter the course of the disease, most particularly surgical resection or radical radiotherapy.’
      • ‘The rest of the pamphlet contained a list of treatment options ranging from modified radical mastectomy to hormonal therapy.’
      • ‘All the control lymph nodes were removed as part of radical surgeries for malignant disease conditions and were negative for malignancy.’
      • ‘Options include radical prostatectomy, conformal radiotherapy or brachytherapy, hormone treatment, and active monitoring.’
      • ‘She continued to practise here, despite further radical surgery for a separate primary carcinoma.’
  • 2Characterized by departure from tradition; innovative or progressive.

    ‘the city is known for its radical approach to transport policy’
    • ‘These twin notions are neither new nor radical, but are rooted in core American values.’
    • ‘Road pricing is a radical solution that primarily is about securing allocative efficiency of scarce resources, namely road space.’
    • ‘For most teachers, then, doing things that make a difference would mean working in radical ways within a mainstream school.’
    • ‘She calls for a radical re-examination of traditional approaches to accountability, transparency and press freedom.’
    • ‘At the time of launch the collaboration between the news and current affairs departments was a radical approach.’
    • ‘That's when the American Medical Association published a radical new recommendation - most Americans should be taking vitamins.’
    • ‘Here we would like to entertain the more radical idea that the underlying laws governing those individual phenomena are themselves of statistical origin.’
    • ‘A radical agenda and innovative ideas for a second term of Labour-led government are being thrashed out by ministers and senior party figures in private this weekend.’
    • ‘Moore's law is not concerned with radical new technologies that could have a dramatic effect.’
    • ‘It is unfortunate that most people are not in a position to come into contact, let alone sympathize, with radical musical ideas.’
    • ‘The resulting album attracted two nominations in the Radio 2 folk awards with its radical approach to traditional music.’
    • ‘This is not such a radical thought; rhythms characterize all living systems, indeed, differentiate them from the non-living.’
    • ‘We will need a fresh and radical approach capable of reaching millions, not thousands, of voters.’
    • ‘A radical alternative to this approach, one that would expose patients to the full price of drugs, is reference pricing.’
    • ‘When von Neumann proposed this architecture in 1945, it was a radical idea.’
    • ‘First, let's mandate a radical redesign of that core user of oil, the automobile.’
    • ‘Given the extent to which it is taken for granted today, it can be difficult to fully appreciate the truly innovative and radical approach Frege took to logic.’
    • ‘Many of the widely known Chinese artists presented variations - some slight, some radical - on the type of work that made their reputation.’
    • ‘His early 1980s TV show seemed radical at the time.’
    • ‘But in New York, the gifted young sculptor became a sort of society vanguardist whose soigne work was rooted in radical ideas that he made palatable.’
    unusual, irregular, unorthodox, unfamiliar, uncommon, uncustomary, unwonted, rare, out of the ordinary, atypical, singular, distinctive, individual, individualistic, free-spirited, alternative, different
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    1. 2.1Advocating or based on thorough or complete political or social change; representing or supporting an extreme or progressive section of a political party.
      ‘a radical American activist’
      • ‘So we can have all sorts of radical parties in politics making change there.’
      • ‘Their passivity is a reflection of the lack of cohesiveness among social groups and radical parties.’
      • ‘But they were captives of the extreme radical elements in their party, for whom the Green movement was not essentially a political cause but a spiritual one.’
      • ‘She was supported by all the left and radical parties including the NSSP as well as all the various bourgeois and petty bourgeois Tamil parties.’
      • ‘Born in 1856, he became a radical social reformer who preached the adage of ‘one caste, one God and one religion for all men’.’
      • ‘Hard-liners formed a radical political party, more extremist than any other.’
      • ‘Wales has always had strong left wing and radical political parties and leaders.’
      • ‘In addition, radical students espousing forms of Marxism, some combined with religious political rhetoric, joined the disaffected.’
      • ‘He's accused of supporting extremists or radical groups in other countries as well, but Colombia is an sufficient place to start.’
      • ‘His billionaire wife is remembered either as very religious or beautiful, but certainly not as a radical political activist.’
      • ‘Later it emerged that they belonged to the radical left-wing organisation November 17.’
      • ‘It was an explicit invitation to the radical students to direct their criticism at the highest leaders of the Party and the State.’
      • ‘Western colonies of radical workers sprang up in the 1880s and 1890s.’
      • ‘The Left Bloc began by bringing together people from different traditions of the radical left in Portugal.’
      • ‘We could well have a more radical left-wing party with some trade union support while on the right the Eurosceptics might have gone and formed a new party.’
      • ‘The more radical Jewish political activists have been involved in unions and socialism.’
      • ‘But history shows that protests are organized first by militant, radical fringe parties and then get taken over by more centrist voices as the movement grows.’
      • ‘She has been the most radical advocate of the party's adoption of an independent stance in elections.’
      • ‘A radical working class carried out a general strike in 1917 and provoked two states of siege.’
      • ‘For socialist and radical parties and movements, 1968 saw a mushrooming in their number and members.’
      revolutionary, progressive, reforming, reformist, revisionist, progressivist
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    2. 2.2British historical Belonging to an extreme section of the Liberal party during the 19th century.
      • ‘He was elected as MP for Stirling Burghs in 1868, and gained a reputation as a radical Liberal.’
  • 3Relating to the root of something, in particular.

    1. 3.1Mathematics Of the root of a number or quantity.
      • ‘The answers are thirteen over four and two plus or minus radical seven.’
    2. 3.2Denoting or relating to the roots of a word.
    3. 3.3Music Belonging to the root of a chord.
    4. 3.4Botany Of, or springing direct from, the root or stem base of a plant.
  • 4North American informal [usually as exclamation] Very good; excellent.

    ‘Okay, then. Seven o'clock. Radical!’
    excellent, wonderful, marvellous, magnificent, superb, splendid, glorious, sublime, lovely, delightful, first-class, first-rate, outstanding
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  • 1A person who advocates thorough or complete political or social reform; a member of a political party or part of a party pursuing such aims.

    • ‘I still remember the confusion I felt the day that a female member of the Dartmouth SDS told me that the only campus radical I considered cool was a male chauvinist.’
    • ‘It was used to crack down on radicals and political dissenters after anarchists exploded a bomb outside the home of Attorney General Mitchell Palmer in 1919.’
    • ‘Because she's a radical, in the true sense: striking at the root.’
    • ‘The parliamentary Greens went along with the radicals because they knew if they didn't the radicals would splinter the party.’
    • ‘Indeed not every eighteenth-century American supported slavery, and some political radicals were extremely critical of the practice.’
    • ‘Hidden within the morally outraged and civilly disobedient radical, in other words, was the soul of a wronged decision theorist.’
    • ‘Throughout American history, reformers and radicals have addressed social problems through civil disobedience and non-violent resistance.’
    • ‘The advisors also discover that McKeene was a political radical in her youth.’
    • ‘Chao was surrounded by the ideas of political radicals and heard songs of protest sung beneath a portrait of Che Guevara.’
    • ‘He attributed the rise of radicals more to social tensions that followed the 1998 economic and political crisis.’
    • ‘The political radicals who ran the French Revolution from 1793 abolished the concept of weeks altogether.’
    • ‘He was essentially a middle-class radical rather than a champion of the working-class claim to representation in parliament.’
    • ‘I try to be a radical in political and social ways, but I'm a terrible conservative when it comes to technology.’
    • ‘The party has not tried to disguise its new deregulatory approach, which is causing unease among party radicals and old-style social democrats.’
    • ‘Throughout our nation's history, radicals and reformers have viewed their movements as profoundly patriotic.’
    • ‘Rohm was not really a social or political radical.’
    • ‘However politically accommodating the radicals are prepared to be, any talk of defending workers interests is enough to send the union leaders into a frenzy.’
    • ‘It was founded by radicals who had been members of the Socialist Workers Party or other political tendencies that had left that organization.’
    • ‘Miller was neither a social radical nor a pioneer of scientific thought.’
    • ‘A subsequent case failed, thanks largely to protests by French political radicals.’
    revolutionary, progressive, reformer, revisionist
    leftist, left-winger, socialist
    militant, zealot, extremist, fanatic, diehard
    ultra, red
    bolshevik, bolshevist
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  • 2Chemistry
    A group of atoms behaving as a unit in a number of compounds.

    See also free radical
    • ‘Examples of compounds or groups that accept anions include the nitrate and hydroxide radicals.’
    • ‘Subsequent oxidation-reduction reactions can also produce superoxide anions, hydrogen peroxide and hydroxyl radicals.’
    • ‘The hydroxyl radical is very damaging and can react with many substances.’
    • ‘The superoxide anion radical is capable of causing as much cellular damage as singlet oxygen.’
    • ‘Marcel Nicolet resolved some of this discrepancy by showing how reactive molecular fragments called radicals convert ozone molecules back into O 2.’
  • 3The root or base form of a word.

    • ‘The word can refer to a geminate verb, i.e., a triliteral verb where the second and third radicals are the same - also called mediae geminatae.’
    1. 3.1Any of the basic set of approximately 214 Chinese characters constituting semantically or functionally significant elements in the composition of other characters and used as a means of classifying characters in dictionaries.
      • ‘There are about 200 radicals representing basic subjects.’
      • ‘It is for this reason also, that the character xin does not contain the radical for ‘body part’, and is the only zang which does not.’
      • ‘Finally, the Lexical Decision test is a measure of children's right-left spatial reversals of Chinese radicals.’
      • ‘By learning the function of radicals of Chinese characters, students can learn new characters by groups and strings.’
      • ‘Sho is an ideograph that is comprised of two radicals meaning ‘cloth’ and ‘knife’.’
      • ‘So you see, by knowing the radicals and the 6 ways of forming Chinese characters, one can pretty much guess the meaning and sound of Chinese characters.’
  • 4Mathematics
    A quantity forming or expressed as the root of another.

    • ‘When the exponent is a prime number, I say that its radical cannot be divisible by any other prime except those that are greater by one than a multiple of double the exponent.’
    • ‘From its true emergence, algebra can be seen as a theory of equations solved by means of radicals, and of algebraic calculations on related expressions.’
    • ‘The paper also shows that if n is a prime less than 10 the equation x n - 1 = 0 can be solved in radicals.’
    • ‘In high school we are taught the quadratic formula which provides the roots of any quadratic equation in terms of radicals involving the coefficients of the equation.’
    • ‘In 1845 Wantzel, continuing his researches into equations, gave a new proof of the impossibility of solving all algebraic equations by radicals.’
    1. 4.1A radical sign.


Late Middle English (in the senses ‘forming the root’ and ‘inherent’): from late Latin radicalis, from Latin radix, radic- root.