arbitrary

American  

[ahr-bi-trer-ee] / ˈɑr bɪˌtrɛr i /

adjective

1. subject to individual will or judgment without restriction; contingent solely upon one's discretion.

   an arbitrary decision.

2. decided by a judge or arbiter rather than by a law or statute.

3. having unlimited power; uncontrolled or unrestricted by law; despotic; tyrannical.

   an arbitrary government.

4. based on whim or personal preference, without reason or pattern; random.

   This is an unusual encyclopedia, arranged by topics in a more or less arbitrary order.

5. Mathematics. undetermined; not assigned a specific value.

   an arbitrary constant.

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noun

plural

arbitraries

1. Printing. arbitraries, (in Britain) peculiar.

arbitrary British  

/ ˈɑːbɪtrərɪ /

adjective

1. founded on or subject to personal whims, prejudices, etc; capricious

2. having only relative application or relevance; not absolute

3. (of a government, ruler, etc) despotic or dictatorial

4. maths not representing any specific value

   an arbitrary constant

5. law (esp of a penalty or punishment) not laid down by statute; within the court's discretion

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Other Word Forms

• arbitrarily adverb
• arbitrariness noun
• nonarbitrary adjective
• unarbitrary adjective

Etymology

Origin of arbitrary

First recorded in 1400–50; late Middle English, from Latin arbitrārius “uncertain” (i.e., depending on an arbiter's decision); arbiter, -ary

Explanation

Something that's arbitrary seems like it's chosen at random instead of following a consistent rule. Team members would dislike their coach using a totally arbitrary method to pick starting players. Even though arbitrary comes from a word meaning "judge" (arbiter), that doesn't mean judges are always fair. Calling a decision-maker arbitrary is usually a negative thing, suggesting the person is making rules based on whim rather than justice. A coach who selects starting players arbitrarily isn't strictly applying a rule; he could just be picking names out of a hat.

Example Sentences

“It’s an arbitrary threshold that serves a few purposes.”

From MarketWatch • Apr. 10, 2026

The A cap seems arbitrary and shifting to A-minuses feels inconsequential, he said.

From The Wall Street Journal • Apr. 3, 2026

The DOJ has long claimed that the policy was not arbitrary but carefully laid out in a May 2025 email about “Courthouse Arrest Guidance and Case Adjudication.”

From Slate • Mar. 27, 2026

In her ruling, she said the government's designation of Anthropic as a supply chain risk was "likely both contrary to law and arbitrary and capricious."

From Barron's • Mar. 26, 2026

There are, of course, exceptions to this rule, such as gold or uranium, elements prized because of arbitrary economic conventions or aesthetic judgments, or because they have remarkable practical applications.

From "Cosmos" by Carl Sagan

Related Words

• capricious
• discretionary
• erratic
• frivolous
• inconsistent
• irrational
• irresponsible
• random
• subjective
• unreasonable
• willful