The Collaborative International Dictionary of English v.0.48:

Seclude \Se*clude\, v. t. [imp. & p. p. Secluded; p. pr. & vb.
   n. Secluding.] [L. secludere, seclusum; pref. se- aside +
   claudere to shut. See Close, v. t.]
   1. To shut up apart from others; to withdraw into, or place
      in, solitude; to separate from society or intercourse with
      others.
      [1913 Webster]

            Let Eastern tyrants from the light of heaven
            Seclude their bosom slaves.           --Thomson.
      [1913 Webster]

   2. To shut or keep out; to exclude. [Obs.] --Evelyn.
      [1913 Webster] -- Se*clud"ed*ly, adv. --
      Se*clud"ed*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

secluded
    adj 1: hidden from general view or use; "a privy place to rest
           and think"; "a secluded romantic spot"; "a secret garden"
           [syn: privy, secluded, secret]
    2: providing privacy or seclusion; "the cloistered academic
       world of books"; "sat close together in the sequestered
       pergola"; "sitting under the reclusive calm of a shade tree";
       "a secluded romantic spot" [syn: cloistered, reclusive,
       secluded, sequestered]

Moby Thesaurus II by Grady Ward, 1.0:

115 Moby Thesaurus words for "secluded":
   abstruse, alone, anonymous, apart, at rest, beclouded, blind,
   buried, calm, cloistered, close, closet, clouded, concealed, cool,
   covered, covert, detached, dwindling, ebbing, eclipsed, eremitic,
   even-tenored, far-off, halcyon, hermetic, hid, hidden, hushed,
   impassive, in a backwater, in a cloud, in a fog, in eclipse,
   in purdah, in the wings, incognito, incommunicado, inmost,
   innermost, insular, interior, intimate, inward, isolated, latent,
   lonely, moldering, monastic, mysterious, obfuscated, obscure,
   obscured, occult, out-of-the-way, out-of-the-world, pacific,
   peaceable, peaceful, personal, placid, private, privy, quarantined,
   quiescent, quiet, recluse, recondite, remote, removed, reposeful,
   reposing, restful, resting, retired, screened, secluse, seclusive,
   secret, segregated, separate, separated, sequestered, sequestrated,
   sheltered, shut off, shy, smooth, solitary, still, still as death,
   stillish, stilly, stoic, stolid, subsiding, tranquil, unagitated,
   under an eclipse, under cover, under house arrest, under wraps,
   underground, undisturbed, unfrequented, unknown, unmoved,
   unperturbed, unruffled, unstirring, untroubled, unvisited, waning,
   withdrawn, wrapped in clouds