The Collaborative International Dictionary of English v.0.48:

Secrecy \Se"cre*cy\, n.; pl. Secrecies. [From Secret.]
   1. The state or quality of being hidden; as, his movements
      were detected in spite of their secrecy.
      [1913 Webster]

            The Lady Anne,
            Whom the king hath in secrecy long married. --Shak.
      [1913 Webster]

   2. That which is concealed; a secret. [R.] --Shak.
      [1913 Webster]

   3. Seclusion; privacy; retirement. "The pensive secrecy of
      desert cell." --Milton.
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   4. The quality of being secretive; fidelity to a secret;
      forbearance of disclosure or discovery.
      [1913 Webster]

            It is not with public as with private prayer; in
            this, rather secrecy is commanded than outward show.
                                                  --Hooker.
      [1913 Webster]

WordNet (r) 3.0 (2006):

secrecy
    n 1: the trait of keeping things secret [syn: secrecy,
         secretiveness, silence]
    2: the condition of being concealed or hidden [syn: privacy,
       privateness, secrecy, concealment]

Moby Thesaurus II by Grady Ward, 1.0:

81 Moby Thesaurus words for "secrecy":
   Jim Crow, apartheid, apartness, burial, burying, censorship,
   clandestineness, clouding, concealedness, concealment,
   confidentiality, confidentially, covering, covering up, covertly,
   covertness, darkening, deception, detachment, disappearance,
   furtively, furtiveness, hiddenness, hiding, hugger-mugger,
   hugger-muggery, hush, hush-hush, immateriality, imperceptibility,
   indiscernibility, interment, invisibility, isolation, isolationism,
   masking, mysteriously, mystery, mystification, nonappearance,
   obscuration, obscurement, occultation, privacy, privately,
   privatism, privatization, putting away, quarantine, recess,
   reclusion, retirement, retreat, rustication, screening, seclusion,
   secretion, secretively, secretiveness, secretly, secretness,
   segregation, separation, sequestration, silence, sneakily,
   splendid isolation, stealth, stealthily, subterfuge, suppression,
   surreptitiously, surreptitiousness, the invisible, the unseen,
   uncommunicativeness, unperceivability, unseeableness,
   unsubstantiality, viewlessness, withdrawal