An Etymological Dictionary of Astronomy and Astrophysics

1. Based on individual will or choice rather than by reason or necessity.
   

   2. Math.: Undetermined; of unspecified value. → arbitrary constant.

Etymology (EN): M.E., from O.Fr. arbitraire or directly from L. arbitrarius “depending on the will, uncertain,” from → ad- “to” + baetere “to come, go.”

Etymology (PE): Kâmsar, literally “at one’s will,” from kâm “desire, wish; cause, reason,” → despite, + sar “person, individual,” originally “→ head.”