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.

Officiate \Of*fi"ci*ate\, v. t.
   To discharge, perform, or supply, as an official duty or
   function. [Obs.]

         Merely to officiate light Round this opacous earth.
                                                  --Milton.

Source : WordNet®

officiate
     v 1: act in an official capacity in a ceremony or religious
          ritual, such as a wedding; "Who officiated at your
          wedding?"
     2: perform duties attached to a particular office or place or
        function; "His wife officiated as his private secretary"
        [syn: {function}]