The Collaborative International Dictionary of English v.0.48:

Signify \Sig"ni*fy\, v. t. [imp. & p. p. Signified; p. pr. &
   vb. n. Signifying.] [F. signifier, L. significare; signum a
   sign + -ficare (in comp.) to make. See Sign, n., and
   -fy.]
   1. To show by a sign; to communicate by any conventional
      token, as words, gestures, signals, or the like; to
      announce; to make known; to declare; to express; as, a
      signified his desire to be present.
      [1913 Webster]

            I 'll to the king; and signify to him
            That thus I have resign'd my charge to you. --Shak.
      [1913 Webster]

            The government should signify to the Protestants of
            Ireland that want of silver is not to be remedied.
                                                  --Swift.
      [1913 Webster]

   2. To mean; to import; to denote; to betoken.
      [1913 Webster]

            He bade her tell him what it signified. --Chaucer.
      [1913 Webster]

            A tale
            Told by an idiot, full of sound and fury,
            Signifying nothing.                   --Shak.
      [1913 Webster]

   Note: Signify is often used impersonally; as, it signifies
         nothing, it does not signify, that is, it is of no
         importance.
         [1913 Webster]

   Syn: To express; manifest; declare; utter; intimate; betoken;
        denote; imply; mean.
        [1913 Webster]

WordNet (r) 3.0 (2006):

signify
    v 1: denote or connote; "`maison' means `house' in French"; "An
         example sentence would show what this word means" [syn:
         mean, intend, signify, stand for]
    2: convey or express a meaning; "These words mean nothing to
       me!"; "What does his strange behavior signify?"
    3: make known with a word or signal; "He signified his wish to
       pay the bill for our meal"