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arbitrary Line breaks: ar¦bi|trary
Pronunciation: /ˈɑːbɪt(rə)ri/

Definition of arbitrary in English:


1Based on random choice or personal whim, rather than any reason or system: an arbitrary decision
More example sentences
  • The numbering of years is a cultural artifact based on some rather arbitrary decisions made along the way.
  • I prefer to have my laws built on reason rather than arbitrary morality.
  • This numbering system is an arbitrary designation based on small amino acid sequence differences.
capricious, whimsical, random, chance, erratic, unpredictable, inconsistent, wild, hit-or-miss, haphazard, casual;
unmotivated, motiveless, unreasoned, unreasonable, unsupported, irrational, illogical, groundless, unjustifiable, unjustified, wanton;
discretionary, personal, subjective
rare discretional
2(Of power or a ruling body) unrestrained and autocratic in the use of authority: a country under arbitrary government
More example sentences
  • 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.
  • Freedom from arbitrary power is a great good - but so is the avoidance of anarchy.
despotic, tyrannical, tyrannous, peremptory, summary, autocratic, dictatorial, authoritarian, draconian, autarchic, anti-democratic;
oppressive, repressive, undemocratic, illiberal;
imperious, domineering, high-handed;
absolute, uncontrolled, unlimited, unrestrained
3 Mathematics (Of a constant or other quantity) of unspecified value.
Example sentences
  • In contemporary frameworks, the rule of generalization invokes a singular term, the arbitrary constant introduced into the text.
  • How you can tell whether a binary number of arbitrary size is divisible by 10 without looking at the whole number?
  • He defined differential operators of arbitrary order D t.


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.

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