arbitrary

UK: /ˈɑː^rbɪtri/ US: /ˈɑrbɪˌtrɛri/ ,(är′bi trer′ē)

Inflections of 'arbitrary' (n): npl: arbitraries

WordReference Random House Learner's Dictionary of American English © 2026

ar•bi•trar•y /ˈɑrbɪˌtrɛri/  adj. 

1. decided on or done by personal discretion, rather than by reason:
   an arbitrary decision.
2. Government having unlimited power; despotic:
   an arbitrary government.
3. capricious;
   unreasonable;
   unsupported:
   an arbitrary demand for obedience.

ar•bi•trar•i•ly /ˌɑrbɪˈtrɛrəli/  adv. 
ar•bi•trar•i•ness, n. [uncountable]

WordReference Random House Unabridged Dictionary of American English © 2026

ar•bi•trar•y  (är′bi trer′ē), adj., n., pl. -trar•ies. 
adj. 

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. Government having unlimited power;
   uncontrolled or unrestricted by law;
   despotic;
   tyrannical:
   an arbitrary government.
4. capricious;
   unreasonable;
   unsupported:
   an arbitrary demand for payment.
5. Mathematics undetermined;
   not assigned a specific value:
   an arbitrary constant.

n. 

6. Printing arbitraries, Print. (in Britain) peculiar (def. 9).

• Latin arbitrārius uncertain (i.e., depending on an arbiter's decision). See arbiter, -ary
• late Middle English 1400–50

ar•bi•trar•i•ly  (är′bi trer′ə lē, är′bi trâr′-), adv.  ar′bi•trar′i•ness, n. 

Collins Concise English Dictionary © HarperCollins Publishers::

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

Etymology: 15th Century: from Latin arbitrārius arranged through arbitration, uncertain