The Collaborative International Dictionary of English v.0.48:

Umpire \Um"pire\, v. t. [imp. & p. p. Umpired; p. pr. & vb. n.
   Umpiring.]
   1. To decide as umpire; to arbitrate; to settle, as a
      dispute.
      [1913 Webster]

            Judges appointed to umpire the matter in contest
            between them, and to decide where the right lies.
                                                  --South.
      [1913 Webster]

   2. To perform the duties of umpire in or for; as, to umpire a
      game. [Colloq.]
      [1913 Webster]