1) From the mis-division of <i>a noumpere</i>; that is non-equal. An umpire was one who acted as an impartial third party in a dispute, making a decision on behalf of one of the contestants. The act of umpiring and the decision were referred to as umpirage.
1343-4 sureit jugge come monepier issi que lez ditz parties osterreint a son accord, Ingleton
c.1490 the matter betwixt my servant and John Forest is put to iiij men and the owmpreght of you, Plompton
1552 bothe the sayd parties are content ... to abide ... the vmperage of Henrye Savill of Bradleye ... the sayd arbitrars and vmper, Stainland
1661 an Umpier chosen by arbitratours, Holmfirth.