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’
    • ‘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.’
    • ‘Both groups would be affected by a radical change in the business climate.’
    • ‘The reason for this kind of fear-mongering is obvious: it's a way to gin up support for radical reforms.’
    • ‘The proposal makes sweeping, radical changes in the law, but the regulatory analysis does not reflect them.’
    • ‘As a result of these classes, Emmy made the radical decision to abandon school teaching and make a career as a mathematician.’
    • ‘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.’
    • ‘The people are exhausted from the radical changes that affect their way of life.’
    • ‘But even here, the radical change began with federal courts taking major areas of public policy away from state legislatures.’
    • ‘This will undergo a radical change, with an extension to the northbound M606 and a new routing system around it.’
    • ‘‘The question,’ he added, ‘is whether the Executive is actually up for radical change?’’
    • ‘Des Ball says the Intelligence system needs radical overhaul.’
    • ‘Meanwhile, dams associated with hydroelectric plants can cause radical disruption of area ecosystems.’
    • ‘Are the arguments of those who predict a radical change in the nature of 21st century wars that groundless after all?’
    • ‘‘This marks a radical change in the paradigm for selling time on television networks,’ he says.’
    • ‘The rest of the time, they assumed that economic rationalism implies support for radical free-market reform.’
    • ‘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.’
    • ‘Fourth, the tax system needs radical reform.’
    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. 1.1 Forming an inherent or fundamental part of the nature of someone or something.
      ‘the assumption of radical differences between the mental attributes of literate and nonliterate peoples’
      • ‘For translators, the radical differences between Chinese and English are a source of despair and opportunity.’
      • ‘It should be easy enough to guess the reason for this radical difference in behaviour.’
      • ‘There's a radical difference between this kind of traditionalist politics and laissez-faire conservative politics.’
      • ‘The following is a marvellous, energizing, healing ceremony that really does make a radical and lasting, difference in your life.’
      • ‘This is the first time we have encountered such radical differences within one lot.’
      • ‘Only those who do not understand the radical difference between the movement of socialist women and bourgeois suffragettes can think this way.’
      • ‘Here, and elsewhere in the installation, one radical difference between the classical and modern sculptures was made evident.’
      • ‘Iceland displays some radical cultural differences with its temporary American inhabitants.’
      • ‘To that end, you'll notice a radical difference in speed and handling depending on the size of the car.’
      • ‘The difference between then and now was so radical he was at loss about what to think.’
      • ‘Since independence, an emergent class structure has become apparent in urban sectors with radical differences in wealth between the rich and poor.’
      • ‘The story also illustrates the most radical difference between mania and hypomania.’
      • ‘These radical differences reveal crucial changes in American culture.’
      • ‘We want to make a radical difference to the prospects and perception of the town.’
      • ‘He said yesterday: ‘Football results do not make a radical difference to society but they can have an impact.’’
      • ‘The radical injustice of early capitalism gave birth to the overcompensation of totalitarian communism.’
      • ‘Note also the radical difference between how our culture defines ‘fashionable’ thinness for men and women.’
      • ‘As for the property rights of authors to their works, the consequences of these differences are radical.’
      • ‘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.’
      • ‘But then again, a subtle difference was preferable to a radical one, and it did give me a short-term confidence boost.’
      fundamental, basic, essential, quintessential
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    2. 1.2 (of surgery or medical treatment) thorough and intended to be completely curative.
      • ‘The same diagnostic delay led to 64 patients having more radical treatment than necessary.’
      • ‘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.’
      • ‘By the seventeenth century, more radical treatments, often chemical, came into fashion and the gentle, gradual, and individualized diet fell out of favour.’
      • ‘All the control lymph nodes were removed as part of radical surgeries for malignant disease conditions and were negative for malignancy.’
      • ‘A radiographic evaluation is not indicated unless radical treatment is being contemplated.’
      • ‘Despite this risk, radical surgery is not indicated for the treatment of this lesion.’
      • ‘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.’
      • ‘The rest of the pamphlet contained a list of treatment options ranging from modified radical mastectomy to hormonal therapy.’
      • ‘In patients who are unfit to have radical surgery, radiotherapy may be administered to the inguinal lymph nodes.’
      • ‘Each of the main treatments radical prostatectomy, radiation therapy, and monitoring has risks.’
      • ‘She continued to practise here, despite further radical surgery for a separate primary carcinoma.’
      • ‘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.’
      • ‘Options include radical prostatectomy, conformal radiotherapy or brachytherapy, hormone treatment, and active monitoring.’
      • ‘For these women the recommended treatment is often modified radical mastectomy.’
      • ‘More serious cancers, however, will require radical surgery, radiotherapy, and chemotherapy.’
      • ‘Urinary incontinence is very common, but most people do not desire or require radical treatment.’
      • ‘Last week, one simple health message dominated the US media: radical prostate surgery for prostate cancer saves lives.’
      • ‘The patient underwent preoperative chemotherapy and subsequent radical hysterectomy and bilateral pelvic lymphadenectomy.’
      • ‘The patient in this case study underwent ablative surgery consisting of a radical hemipelvectomy carried out by an orthopaedic oncologist.’
      • ‘Men could then be offered radical surgery if their test results showed a worsening trend.’
  • 2Advocating 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’
    • ‘Their passivity is a reflection of the lack of cohesiveness among social groups and radical parties.’
    • ‘Hard-liners formed a radical political party, more extremist than any other.’
    • ‘The more radical Jewish political activists have been involved in unions and socialism.’
    • ‘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.’
    • ‘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.’
    • ‘He's accused of supporting extremists or radical groups in other countries as well, but Colombia is an sufficient place to start.’
    • ‘A radical working class carried out a general strike in 1917 and provoked two states of siege.’
    • ‘So we can have all sorts of radical parties in politics making change there.’
    • ‘His billionaire wife is remembered either as very religious or beautiful, but certainly not as a radical political activist.’
    • ‘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’.’
    • ‘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.’
    • ‘Wales has always had strong left wing and radical political parties and leaders.’
    • ‘For socialist and radical parties and movements, 1968 saw a mushrooming in their number and members.’
    • ‘She has been the most radical advocate of the party's adoption of an independent stance in elections.’
    • ‘The Left Bloc began by bringing together people from different traditions of the radical left in Portugal.’
    • ‘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.’
    • ‘In addition, radical students espousing forms of Marxism, some combined with religious political rhetoric, joined the disaffected.’
    • ‘Later it emerged that they belonged to the radical left-wing organisation November 17.’
    revolutionary, progressive, reforming, reformist, revisionist, progressivist
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    1. 2.1 Characterized by independence of or departure from tradition; innovative or unorthodox.
      ‘the daring, avant-garde spirit of the music was too radical for the conservative audience’
      • ‘The resulting album attracted two nominations in the Radio 2 folk awards with its radical approach to traditional music.’
      • ‘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.’
      • ‘Road pricing is a radical solution that primarily is about securing allocative efficiency of scarce resources, namely road space.’
      • ‘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.’
      • ‘That's when the American Medical Association published a radical new recommendation - most Americans should be taking vitamins.’
      • ‘A radical alternative to this approach, one that would expose patients to the full price of drugs, is reference pricing.’
      • ‘These twin notions are neither new nor radical, but are rooted in core American values.’
      • ‘This is not such a radical thought; rhythms characterize all living systems, indeed, differentiate them from the non-living.’
      • ‘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.’
      • ‘We will need a fresh and radical approach capable of reaching millions, not thousands, of voters.’
      • ‘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.’
      • ‘Many of the widely known Chinese artists presented variations - some slight, some radical - on the type of work that made their reputation.’
      • ‘Moore's law is not concerned with radical new technologies that could have a dramatic effect.’
      • ‘At the time of launch the collaboration between the news and current affairs departments was a radical approach.’
      • ‘His early 1980s TV show seemed radical at the time.’
      • ‘For most teachers, then, doing things that make a difference would mean working in radical ways within a mainstream school.’
      • ‘It is unfortunate that most people are not in a position to come into contact, let alone sympathize, with radical musical ideas.’
      • ‘She calls for a radical re-examination of traditional approaches to accountability, transparency and press freedom.’
      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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  • 3Linguistics
    Denoting or relating to the roots of a word.

    1. 3.1Music Belonging to the root of a chord.
  • 4Mathematics
    Of the root of a number or quantity.

    • ‘The answers are thirteen over four and two plus or minus radical seven.’
  • 5Botany
    Of, or springing direct from, the root or stem base of a plant.

  • 6North 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.

    • ‘Indeed not every eighteenth-century American supported slavery, and some political radicals were extremely critical of the practice.’
    • ‘He was essentially a middle-class radical rather than a champion of the working-class claim to representation in parliament.’
    • ‘Throughout American history, reformers and radicals have addressed social problems through civil disobedience and non-violent resistance.’
    • ‘The political radicals who ran the French Revolution from 1793 abolished the concept of weeks altogether.’
    • ‘Throughout our nation's history, radicals and reformers have viewed their movements as profoundly patriotic.’
    • ‘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.’
    • ‘I try to be a radical in political and social ways, but I'm a terrible conservative when it comes to technology.’
    • ‘Rohm was not really a social or political radical.’
    • ‘The parliamentary Greens went along with the radicals because they knew if they didn't the radicals would splinter the party.’
    • ‘Because she's a radical, in the true sense: striking at the root.’
    • ‘He attributed the rise of radicals more to social tensions that followed the 1998 economic and political crisis.’
    • ‘A subsequent case failed, thanks largely to protests by French political radicals.’
    • ‘It was founded by radicals who had been members of the Socialist Workers Party or other political tendencies that had left that organization.’
    • ‘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.’
    • ‘The advisors also discover that McKeene was a political radical in her youth.’
    • ‘The party has not tried to disguise its new deregulatory approach, which is causing unease among party radicals and old-style social democrats.’
    • ‘Chao was surrounded by the ideas of political radicals and heard songs of protest sung beneath a portrait of Che Guevara.’
    • ‘Hidden within the morally outraged and civilly disobedient radical, in other words, was the soul of a wronged decision theorist.’
    • ‘Miller was neither a social radical nor a pioneer of scientific thought.’
    • ‘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.’
    revolutionary, progressive, reformer, revisionist
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  • 2Chemistry
    A group of atoms behaving as a unit in a number of compounds.

    See also free radical
    • ‘Marcel Nicolet resolved some of this discrepancy by showing how reactive molecular fragments called radicals convert ozone molecules back into O 2.’
    • ‘The superoxide anion radical is capable of causing as much cellular damage as singlet oxygen.’
    • ‘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.’
  • 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. 3.1 Any of the basic set of 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.
      • ‘Sho is an ideograph that is comprised of two radicals meaning ‘cloth’ and ‘knife’.’
      • ‘By learning the function of radicals of Chinese characters, students can learn new characters by groups and strings.’
      • ‘There are about 200 radicals representing basic subjects.’
      • ‘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.’
      • ‘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.’
  • 4Mathematics
    A quantity forming or expressed as the root of another.

    • ‘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.’
    • ‘The paper also shows that if n is a prime less than 10 the equation x n - 1 = 0 can be solved in radicals.’
    • ‘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.’
    • ‘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.’
    1. 4.1 A radical sign.


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