The Collaborative International Dictionary of English v.0.48:

Announcement \An*nounce"ment\, n.
   The act of announcing, or giving notice; that which
   announces; proclamation; publication.
   [1913 Webster]

WordNet (r) 3.0 (2006):

announcement
    n 1: a formal public statement; "the government made an
         announcement about changes in the drug war"; "a declaration
         of independence" [syn: announcement, proclamation,
         annunciation, declaration]
    2: a public statement containing information about an event that
       has happened or is going to happen; "the announcement
       appeared in the local newspaper"; "the promulgation was
       written in English" [syn: announcement, promulgation]

Moby Thesaurus II by Grady Ward, 1.0:

110 Moby Thesaurus words for "announcement":
   account, acquaintance, ad, advert, advertisement, affirmance,
   affirmation, allegation, annunciation, assertion, asseveration,
   averment, avouchment, avowal, blue book, briefing, broadcast,
   bulletin, bulletin board, circular, commercial, communication,
   communique, conclusion, conveyance, creed, data, datum,
   declaration, dictum, directory, disclosure, dispatch, edict,
   encyclical, enlightenment, enunciation, evidence, facts,
   factual information, familiarization, gen, general information,
   giving, guidebook, handout, hard information, impartation,
   imparting, impartment, incidental information, info, information,
   instruction, intelligence, ipse dixit, knowledge, light, manifesto,
   mention, message, notice, notification, position, position paper,
   positive declaration, predicate, predication, presentation,
   proclamation, profession, program, programma, promotional material,
   promulgation, pronouncement, pronunciamento, proof, proposition,
   protest, protestation, public notice, publication, publicity,
   release, report, say, say-so, saying, sharing, sidelight, spot,
   stance, stand, statement, telling, the dope, the goods, the know,
   the scoop, transfer, transference, transmission, transmittal,
   ukase, utterance, vouch, white book, white paper, word