What does arbitrary mean?
Arbitrary is an adjective describing something determined by chance, whim, or individual preference rather than by reason, rule, or principle. An arbitrary decision is one that cannot be justified by evidence or logic — it simply reflects someone's choice in the moment. The word carries strongly negative connotations in law and politics, where arbitrary power means authority exercised without accountability or respect for rights, as in arbitrary arrests or rulings. Yet in technical fields such as mathematics and computer science, arbitrary is often neutral: an 'arbitrary value' is merely one selected freely or left unspecified. The term derives from Latin arbiter, meaning judge, which gives it an ironic history — a word rooted in fair judgment now most often signals its absence. Understanding arbitrary helps readers evaluate whether decisions around them rest on genuine reasoning or on unexamined preference.
adjectiveBased on random choice or personal whim rather than any reason, system, or principle. In legal and political contexts, it also describes the unjust exercise of power without regard for established rules or people's rights.
- Based on random choice, whim, or personal preference rather than reason or a fixed principle.
- (of power or authority) Exercised without constraint of law or regard for fairness; despotic or unaccountable.
"The referee's decision to award a penalty seemed entirely arbitrary."
"Choosing the meeting time seemed completely arbitrary — no one could explain why 3 p.m. had been picked."
"Critics condemned the government's arbitrary detention of journalists without trial."
The word 'arbitrary' comes from the same Latin root as 'arbiter' — a judge — yet today it describes decisions made with no judgment at all.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of arbitrary
Arbitrary entered English in the early 15th century from Latin arbitrarius, meaning 'depending on the judgment or will of an arbiter'. The Latin root arbor/arbiter relates to judging and decision-making, and it also gave rise to related English words such as arbitrate, arbitration, and arbiter itself. Over time, the sense shifted from 'dependent on judgment' toward 'dependent on mere will or chance', producing the modern negative connotation of decisions made without reason or restraint.
Related word forms
How arbitrary is actually used
Arbitrary is common in both everyday and formal contexts. It often carries a negative connotation, implying unfairness or lack of justification, especially in legal and political discourse. In mathematics and computing, 'arbitrary' can be neutral, simply meaning unspecified or chosen freely (e.g., 'an arbitrary constant').
Easily confused with arbitrary
Arbitrate is a verb meaning to settle a dispute by acting as an impartial judge, while arbitrary is an adjective describing something decided on whim or without reason.