c.1400, noumper, from O.Fr. nonper "odd number, not even," in reference to a third person to arbitrate between two, from non "not" + per "equal," from L. par. Initial -n- lost by c.1440 due to faulty separation of a noumpere, heard as an oumpere. Originally legal, the gaming sense first recorded 1714 (in wrestling). Short form ump is attested from 1915. The verb is first recorded 1609, from the noun.