1. to act as arbiter upon (a disputed question) : to settle (a dispute between two people or groups) after hearing the arguments and opinions of both. To make an official decision that ends a legal disagreement between people or groups without the need for the disagreement to be solved in court.Arbitrate is when a neutral third party helps end a conflict. Arbitrate derives from the Latin arbiter "judge. There are five meanings listed in OED's entry for the verb arbitrate. The Book in 3 Sentences. A very, very detailed account of the Western Hemisphere in the American revolutionary period.