The Collaborative International Dictionary of English v.0.48:

Denounce \De*nounce"\, v. t. [imp. & p. p. Denounced; p. pr. &
   vb. n. Denouncing.] [F. d['e]noncer, OF. denoncier, fr. L.
   denuntiare, denunciare; de- + nunciare, nuntiare, to
   announce, report, nuntius a messenger, message. See Nuncio,
   and cf. Denunciate.]
   1. To make known in a solemn or official manner; to declare;
      to proclaim (especially an evil). [Obs.]
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            Denouncing wrath to come.             --Milton.
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            I denounce unto you this day, that ye shall surely
            perish.                               --Deut. xxx.
                                                  18.
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   2. To proclaim in a threatening manner; to threaten by some
      outward sign or expression.
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            His look denounced desperate.         --Milton.
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   3. To point out as deserving of reprehension or punishment,
      etc.; to accuse in a threatening manner; to invoke censure
      upon; to stigmatize.
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            Denounced for a heretic.              --Sir T. More.
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            To denounce the immoralities of Julius C[ae]sar.
                                                  --Brougham.
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WordNet (r) 3.0 (2006):

denounce
    v 1: speak out against; "He denounced the Nazis"
    2: to accuse or condemn or openly or formally or brand as
       disgraceful; "He denounced the government action"; "She was
       stigmatized by society because she had a child out of
       wedlock" [syn: stigmatize, stigmatise, brand,
       denounce, mark]
    3: announce the termination of, as of treaties
    4: give away information about somebody; "He told on his
       classmate who had cheated on the exam" [syn: denounce,
       tell on, betray, give away, rat, grass, shit,
       shop, snitch, stag]