Definition of arbitrary in English:



  • 1Based on random choice or personal whim, rather than any reason or system.

    ‘an arbitrary decision’
    • ‘The numbering of years is a cultural artifact based on some rather arbitrary decisions made along the way.’
    • ‘But Plato tells us that the ethical laws cannot be the arbitrary whims of personalized gods.’
    • ‘So, here I would only talk about a few rather arbitrary points that have occupied my mind in the recent days and leave the rest to other people to explore.’
    • ‘The historical reason for this time limit was based on arbitrary precedent.’
    • ‘Any system of classification is arbitrary and thus frail, subject to the contradictions of experience.’
    • ‘Yes, this requires work - but that is what makes it a justice system rather than one of arbitrary punishment.’
    • ‘Citizens, too, began to complain that the economic system was bafflingly arbitrary.’
    • ‘The question seemed rather arbitrary with no rhyme or reason whatsoever.’
    • ‘They become a matter of subjective and arbitrary whim if they are cut off from collective deliberations.’
    • ‘Make sure the decision about who goes is not arbitrary or based on favoritism.’
    • ‘Capricious and arbitrary as the system might be, it serves several contradictory needs at once.’
    • ‘That was the system - arbitrary, incomprehensible, illogical - and fairness had nothing to do with it.’
    • ‘Police officers cannot take arbitrary measures based on suspicion.’
    • ‘Why couldn't people see that tradition, while rather arbitrary, was the only fair way to do things?’
    • ‘I prefer to have my laws built on reason rather than arbitrary morality.’
    • ‘This system was so arbitrary and irrational that it resulted in large numbers of poor persons being excluded.’
    • ‘It has been said more than once that 10 seems a rather arbitrary number, and it has not been clear how the authors of the law arrived at it.’
    • ‘His either/or choice was arbitrary and unnecessary, and he hurt his organization as a result.’
    • ‘This numbering system is an arbitrary designation based on small amino acid sequence differences.’
    • ‘The use of the severity and rarity criteria has meant that arbitrary and unjust decisions have been applied to many claims.’
    capricious, whimsical, random, chance, erratic, unpredictable, inconsistent, wild, hit-or-miss, haphazard, casual
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  • 2(of power or a ruling body) unrestrained and autocratic in the use of authority.

    ‘a country under arbitrary government’
    • ‘These kings have not unlimited or arbitrary power, and the generals do more by example than by authority.’
    • ‘By the time of the Revolution, the standing army had become a symbol of repressive authority and arbitrary rule.’
    • ‘So too, one might think that an organized police force poses less of a threat of arbitrary power than a volunteer force.’
    • ‘Freedom from arbitrary power is a great good - but so is the avoidance of anarchy.’
    • ‘But why should we give that arbitrary power to any civil servant?’
    • ‘They have, I believe, lost their way and taken a path that can only lead back to the supremacy of arbitrary power.’
    • ‘It also meant freedom from arbitrary power, which by 1792 was being routinely identified as the power of any king.’
    • ‘If not, what is to prevent the exercise of excessive or arbitrary power?’
    • ‘In the fourteenth century, two parallel movements were under way to enforce Magna Carta's curbs on arbitrary royal authority.’
    • ‘The following films deal with rebellion against arbitrary or repressive authority.’
    • ‘A right of access to a court is one of the checks on the danger of arbitrary power.…’
    • ‘The very idea of the rule of law is partly derived from the conclusion that it is reasonable and morally good to limit arbitrary power.’
    • ‘To put those forms of authority on the same register as the state and-worse-subject them all to the arbitrary power of the state is not helpful.’
    • ‘Thus a major new avenue of arbitrary government power would be opened up.’
    • ‘He was an eloquent opponent of the exercise of arbitrary power by governments the world over.’
    • ‘Curbs were placed on the arbitrary exercise of power and steps were taken to give some measure of regularity to the legal system.’
    despotic, tyrannical, tyrannous, peremptory, summary, autocratic, dictatorial, authoritarian, draconian, autarchic, anti-democratic
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  • 3Mathematics
    (of a constant or other quantity) of unspecified value.

    • ‘To each triangle, there exists a similar triangle of arbitrary magnitude.’
    • ‘In contemporary frameworks, the rule of generalization invokes a singular term, the arbitrary constant introduced into the text.’
    • ‘He defined differential operators of arbitrary order D t.’
    • ‘How you can tell whether a binary number of arbitrary size is divisible by 10 without looking at the whole number?’
    • ‘For tabular presentation we used arbitrary cut off values.’


Late Middle English (in the sense ‘dependent on one's will or pleasure, discretionary’): from Latin arbitrarius, from arbiter ‘judge, supreme ruler’, perhaps influenced by French arbitraire.