Thesaurus entry:
arbitrary
adjective
1. Determined or marked by whim or caprice rather than reason: capricious, whimsical. See surprise
2. Based on individual judgment or discretion: discretionary, judgmental, personal, subjective. See opinion, surprise
3. Having and exercising complete political power and control: absolute, absolutistic, autarchic, autarchical, autocratic, autocratical, despotic, dictatorial, monocratic, totalitarian, tyrannic, tyrannical, tyrannous. See over, politics