The Collaborative International Dictionary of English v.0.48:

Ascribe \As*cribe"\, v. t. [imp. & p. p. Ascribed; p. pr. &
   vb. n. Ascribing.] [L. ascribere, adscribere, to ascribe;
   ad + scribere to write: cf. OF. ascrire. See Scribe.]
   1. To attribute, impute, or refer, as to a cause; as, his
      death was ascribed to a poison; to ascribe an effect to
      the right cause; to ascribe such a book to such an author.
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            The finest [speech] that is ascribed to Satan in the
            whole poem.                           --Addison.
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   2. To attribute, as a quality, or an appurtenance; to
      consider or allege to belong.
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   Syn: To Ascribe, Attribute, Impute.

   Usage: Attribute denotes, 1. To refer some quality or
          attribute to a being; as, to attribute power to God.
          2. To refer something to its cause or source; as, to
          attribute a backward spring to icebergs off the coast.
          Ascribe is used equally in both these senses, but
          involves a different image. To impute usually denotes
          to ascribe something doubtful or wrong, and hence, in
          general literature, has commonly a bad sense; as, to
          impute unworthy motives. The theological sense of
          impute is not here taken into view.
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                More than good-will to me attribute naught.
                                                  --Spenser.
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                Ascribes his gettings to his parts and merit.
                                                  --Pope.
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                And fairly quit him of the imputed blame.
                                                  --Spenser.
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WordNet (r) 3.0 (2006):

ascribe
    v 1: attribute or credit to; "We attributed this quotation to
         Shakespeare"; "People impute great cleverness to cats"
         [syn: impute, ascribe, assign, attribute]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "ascribe":
   accredit, adduce, advance, affix, allege, apply, assign, attach,
   attach to, attribute, charge, cite, conjecture, connect with,
   credit, fasten, fix, give, guess, impute, lay, pin on, place, put,
   refer, saddle, surmise