Source : Webster's Revised Unabridged Dictionary (1913)

Antedate \An"te*date`\, n.
   1. Prior date; a date antecedent to another which is the
      actual date.

   2. Anticipation. [Obs.] --Donne.

Antedate \An"te*date`\, v. t. [imp. & p. p. {Antedated}; p. pr.
   & vb. n. {Antedating}.]
   1. To date before the true time; to assign to an earlier
      date; thus, to antedate a deed or a bond is to give it a
      date anterior to the true time of its execution.

   2. To precede in time.

   3. To anticipate; to make before the true time.

            And antedate the bliss above.         --Pope.

            Who rather rose the day to antedate.  --Wordsworth.

Source : WordNet®

antedate
     v 1: be earlier in time; go back further; "Stone tools precede
          bronze tools" [syn: {predate}, {precede}, {forego}, {antecede}]
          [ant: {postdate}]
     2: establish something as being earlier relative to something
        else [syn: {predate}, {foredate}] [ant: {postdate}]