Arbiter Definition: An alternate term for arbitrator; preferred in some jurisdictions such as Scotland. Same as arbitrator; the presiding and deciding officer(s) of an arbitration. Scotland has a few twists in alternative dispute resolution terminology. Preferring arbiter to arbitrator is one; using the term oversman (umpire) is another. Some translation of Roman law documents, such as the Twelve Tables, defer to this spelling as well: arbiter. The Romans used the word arbiter interchangeably with judex to refer to the office of judge in early Roman law. Categories & Topics: Alternative Dispute Resolution (ADR) Law Dictionary Find you are constantly looking up definitions? Try our search provider (works in most modern browsers) If you find an error or omission in Duhaime's Legal Dictionary, or if you have legal term suggestion, we'd love to hear from you!