Merriam-Webster Collegiate Dictionary - arbitrary

 adjective  Date: 15th century  1. depending on individual discretion (as of a judge) and not fixed by law the manner of punishment is ~  2.  a. not restrained or limited in the exercise of power ; ruling by absolute authority an ~ government  b. marked by or resulting from the unrestrained and often tyrannical exercise of power protection from ~ arrest and detention  3.  a. based on or determined by individual preference or convenience rather than by necessity or the intrinsic nature of something an ~ standard take any ~ positive number ~ 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 ~ — Nehemiah Jordan  • arbitrarily adverb  • arbitrariness noun