(adj.adv.) : arbītrārĭus, a, um, adj.arbiter.
* Of arbitration, arbitrating, done by way of arbitration: formula, Gai Inst. 4, 163: actio,Dig. 13, 4, 2; cf. Zimmern, Rechtsgesch. 3 B, §§ 67 and 68.—Hence
* Transf.
* In Plaut. (with ref. to the distinction in law lang. between certus and arbitrarius: judicium est pecuniae certae, arbitrium incertae,Cic. Rosc. Com. 4; cf. Zimmern, Rechtsgesch. 3 B, § 57) = incertus, uncertain, not sure: hoc certum est, non arbitrarium,Plaut. Am. 1, 1, 216.—Adv.: arbītrārĭō: nunc pol ego perii certo, non arbitrario,there's no mistake about it,Plaut. Poen. 3, 5, 42 (the only adv. of this word in use).
* Depending on the will, arbitrary (cf. precarius): motus in arteriā naturalis, non arbitrarius,Gell. 18, 10 fin.

s. TLL