Source : Webster's Revised Unabridged Dictionary (1913)

Officiate \Of*fi"ci*ate\, v. i. [imp. & p. p. {Officiated}; p.
   pr. & vb. n. {Officiating}.] [LL. officiare. See {Office}.]
   To act as an officer in performing a duty; to transact the
   business of an office or public trust; to conduct a public
   service. --Bp. Stillingfleet.

Source : WordNet®

officiating
     n : the act of umpiring; "the officiating was excellent" [syn: {umpirage},
          {officiation}, {refereeing}]