The Collaborative International Dictionary of English v.0.48:

Presuppose \Pre`sup*pose"\, v. t. [imp. & p. p. Presupposed;
   p. pr. & vb. n. Presupposing.] [Pref. pre- + suppose: cf.
   F. pr['e]supposer.]
   To suppose beforehand; to imply as antecedent; to take for
   granted; to assume; as, creation presupposes a creator.
   [1913 Webster]

         Each [kind of knowledge] presupposes many necessary
         things learned in other sciences, and known beforehand.
                                                  --Hooker.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "presupposed":
   assumed, forejudged, hinted, implicated, implied, indicated,
   inferred, intimated, involved, judged beforehand, meant,
   preconceived, preconceptual, preconcluded, predecided,
   predetermined, predisposed, predispositional, prejudged,
   prejudging, prejudicial, presumed, presurmised, suggested,
   supposed