Synonyms of arbitrary

2 Syllables

willful, seton, random, pricey, driftless, unfair, freakish, thetic, pricier, offhand, fickler, wayward

3 Syllables

frivolous, fanciful, optional, erratic, objectless, thetical, capricious, unsporting, unaimed, overkill, tyrannous, wrong-headed, magistral, crack-the-whip, czarlike, haphazard, fortuitous, whimsical, dogmatic, prescribed, ruffianly, vagarious, lucky-dog, hit-or-miss, summary, hard-shelled

4 Syllables

unscientific, predominant, autocratic, absolutist, irrational, uncontested, dictative, humorsome, monocratic, supercilious, subjective, dictatorial, injudicious, peremptory, superficial, all-powerful, undisputed, helter-skelter, hurry-scurry, unchallenged, discretional, unreasoned, inconsistent

5 Syllables

unreasonable, approximate, unaccountable, inequitable, opinionated, irresponsible, noncompulsory, discretionary

6 Syllables

nonobligatory