The Collaborative International Dictionary of English v.0.48:

Predate \Pre*date"\, v. t.
   To date anticipation; to affix to (a document) an earlier
   than the actual date; to antedate; as, a predated deed or
   letter.
   [1913 Webster]

WordNet (r) 3.0 (2006):

predate
    v 1: be earlier in time; go back further; "Stone tools precede
         bronze tools" [syn: predate, precede, forego,
         forgo, antecede, antedate] [ant: follow,
         postdate]
    2: come before; "Most English adjectives precede the noun they
       modify" [syn: precede, predate]
    3: prey on or hunt for; "These mammals predate certain eggs"
       [syn: raven, prey, predate]
    4: establish something as being earlier relative to something
       else [syn: predate, antedate, foredate] [ant:
       postdate]

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "predate":
   announce, antecede, antedate, anticipate, backdate, be before,
   be dated, be early, bear date, come before, date, date at,
   date-stamp, dateline, datemark, forerun, go before, herald,
   make a date, pace, postdate, precede, precurse, preexist, proclaim,
   set the date, update, usher in