: not planned or chosen for a particular reason : not based on reason or evidence
: done without concern for what is fair or right
Full Definition of ARBITRARY
: depending on individual discretion (as of a judge) and not fixed by law <the manner of punishment is arbitrary>
a: not restrained or limited in the exercise of power : ruling by absolute authority <an arbitrary government>
b: marked by or resulting from the unrestrained and often tyrannical exercise of power <protection from arbitrary arrest and detention>
a: based on or determined by individual preference or convenience rather than by necessity or the intrinsic nature of something <an arbitrary standard><take any arbitrary positive number><arbitrary division of historical studies into watertight compartments — A. J. Toynbee>
b: existing or coming about seemingly at random or by chance or as a capricious and unreasonable act of will <when a task is not seen in a meaningful context it is experienced as being arbitrary — Nehemiah Jordan>
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.
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