arbitrary
adjective
ar·bi·trary
ˈär-bə-ˌtrer-ē 
-ˌtre-rē
1
a
: chosen, decided, etc. seemingly at random or on a whim rather than in a reasoned or methodical way
Until we understand it, advice on which foods to eat … will always seem arbitrary …—
Nicholas Florko
Nicholas FlorkoYou can tell a well-written show when you realize not a single note, word or marking is arbitrary.—Charlie Henderson, quoted in The Hamilton (Ontario) Spectator
Charlie Henderson, quoted in The Hamilton (Ontario) Spectator
also
: random entry 1 sense 1
… passwords are child's play for computer criminals—particularly if the password is an actual word rather than an arbitrary string of letters and numbers. —Stephen T. Irwin
Stephen T. Irwin
b
: based on or determined by individual preference or convenience rather than by necessity or the intrinsic value of something
an arbitrary deadline
… Einstein added to the equation … the Greek symbol lambda (Λ), an arbitrary mathematical shorthand for whatever was keeping the universe in perfect balance.—Richard Panek
Richard Panek2
a
: not restrained or limited in the exercise of power : ruling by absolute authority
I am … a mortal Enemy to arbitrary Government and unlimited Power.—Silence Dogood (Benjamin Franklin)
Silence Dogood (Benjamin Franklin)
b
: marked by or resulting from the unrestrained and often tyrannical exercise of power
protection from arbitrary arrest and detention
3
law
: depending on individual discretion (as of a judge) and not fixed by law
They argue … that the right to be free from deprivations of liberty as a result of arbitrary sentences is fundamental …—Chapman et al. v. U.S., 500 U.S. 453 (1991)
Chapman et al. v. U.S., 500 U.S. 453 (1991)
Did you know?
Donning black robes and a powdered wig to learn about arbitrary might seem to be an arbitrary—that is, random or capricious—choice, but it would in fact jibe with the word’s etymology. Arbitrary comes from the Latin noun arbiter, which means “judge” and is the source of the English word arbiter, also meaning “judge.” In English, arbitrary first meant “depending upon choice or discretion” and was specifically used to indicate the sort of decision (as for punishment) left up to the expert determination of a judge rather than defined by law. Today, it can also be used for anything determined by or as if by chance or whim.
Examples of arbitrary in a Sentence
U.S. News was revealed to have considered assigning in its next rankings an arbitrary SAT score to Sarah Lawrence College because the school no longer collects applicants' scores.
—Julie Rawe, Time, 2 Apr. 2007
Darwin's emphasis on how populations gradually change gave the notion of species a more arbitrary quality: Species had whatever boundaries taxonomists chose. The idea of a species as a population of individuals that breed mostly with each other comes from 20th-century theorists.
—S. Milius, Science News, 25 Mar. 2006
The Marriage Act certainly employed arbitrary and draconian means. It forced all couples to marry between 8 am and 12 noon, according to the rites of the established Church of England, in one of their respective local parish churches.
—David Johnson, History Today, November 2003
Two days after President Lincoln issued the first version of his Emancipation Proclamation, he suspended the right of habeas corpus for anyone accused of resisting the draft or discouraging enlistment. Hundreds of civilians were arrested, some for good reasons, some for entirely arbitrary and personal ones.
—Michael Lesy, Double Take, Spring 2001
An arbitrary number has been assigned to each district.
I don't know why I chose that one; it was a completely arbitrary decision.
Although arbitrary arrests are illegal, they continue to occur in many parts of the country.
Julie Rawe, Time, 2 Apr. 2007
Darwin's emphasis on how populations gradually change gave the notion of species a more arbitrary quality: Species had whatever boundaries taxonomists chose. The idea of a species as a population of individuals that breed mostly with each other comes from 20th-century theorists.
—S. Milius, Science News, 25 Mar. 2006
The Marriage Act certainly employed arbitrary and draconian means. It forced all couples to marry between 8 am and 12 noon, according to the rites of the established Church of England, in one of their respective local parish churches.
—David Johnson, History Today, November 2003
Two days after President Lincoln issued the first version of his Emancipation Proclamation, he suspended the right of habeas corpus for anyone accused of resisting the draft or discouraging enlistment. Hundreds of civilians were arrested, some for good reasons, some for entirely arbitrary and personal ones.
—Michael Lesy, Double Take, Spring 2001
An arbitrary number has been assigned to each district.
I don't know why I chose that one; it was a completely arbitrary decision.
Although arbitrary arrests are illegal, they continue to occur in many parts of the country.
Recent Examples on the Web
There was something arbitrary about the way this term and its synonyms were bandied about.
—Literary Hub, 5 Nov. 2025
Under Chaikesh’s leadership, the company created large pricing models, a framework that prices information based on real-time metrics of supply, demand, and quality signals instead of using arbitrary metrics like user clicks or page (or social media) views.
—Matthew Kayser, USA Today, 4 Nov. 2025
Yet, the severity of gendered crime during Partition wasn’t caused by an arbitrary upsurge of madness.
—JSTOR Daily, 30 Oct. 2025
Several lawsuits have already been filed challenging the fee and selection changes, with universities, labor groups, and business organizations arguing that the administration exceeded its authority and that the new rules are arbitrary.
—Billal Rahman, MSNBC Newsweek, 27 Oct. 2025
See All Example Sentences for arbitrary
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Literary Hub, 5 Nov. 2025
Under Chaikesh’s leadership, the company created large pricing models, a framework that prices information based on real-time metrics of supply, demand, and quality signals instead of using arbitrary metrics like user clicks or page (or social media) views.
—Matthew Kayser, USA Today, 4 Nov. 2025
Yet, the severity of gendered crime during Partition wasn’t caused by an arbitrary upsurge of madness.
—JSTOR Daily, 30 Oct. 2025
Several lawsuits have already been filed challenging the fee and selection changes, with universities, labor groups, and business organizations arguing that the administration exceeded its authority and that the new rules are arbitrary.
—Billal Rahman, MSNBC Newsweek, 27 Oct. 2025
See All Example Sentences for arbitrary
Cite this Entry
“Arbitrary.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/arbitrary. Accessed 7 Nov. 2025.
Copy CitationKids Definition
arbitrary
adjective
ar·bi·trary
ˈär-bə-ˌtrer-ē
1
: coming from or given to free exercise of the will without thought of fairness or right
an arbitrary punishment
an arbitrary ruler
2
a
: based on or determined by a person's preference or opinion
an arbitrary choice
b
: seeming to have been chosen by chance
an arbitrary sampling
arbitrariness
noun
ˈär-bə-ˌtrer-ē-nəs
Legal Definition
arbitrary
adjective
ar·bi·trary
ˈär-bə-ˌtrer-ē
1
: depending on individual discretion (as of a judge) and not fixed by standards, rules, or law
the manner of punishment is arbitrary
2
a
: not restrained or limited in the exercise of power
an arbitrary government
b
: marked by or resulting from the unrestrained exercise of power
protection from arbitrary arrest and detention
3
a
: based on preference, bias, prejudice, or convenience rather than on reason or fact
an arbitrary standard
different provisions for the married and the unmarried were irrational and arbitrary—K. A. Cohen
K. A. Cohen
b
: existing or coming about seemingly at random or by chance or as an unreasonable act of individual will without regard for facts or applicable law
—often used in the phrase arbitrary and capricious
an agency finding or conclusion of lack of evidence would be arbitrary and capricious if the record afforded no substantial basis for such a finding—Irvin v. Hobby, 131 F. Supp. 851 (1955)
Irvin v. Hobby, 131 F. Supp. 851 (1955)Note: Under section 706 of the Administrative Procedure Act, a court shall set aside an agency's action, findings, or conclusions determined upon review to be arbitrary.
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