The Collaborative International Dictionary of English v.0.48:

Shelter \Shel"ter\, v. t. [imp. & p. p. Sheltered; p. pr. &
   vb. n. Sheltering.]
   1. To be a shelter for; to provide with a shelter; to cover
      from injury or annoyance; to shield; to protect.
      [1913 Webster]

            Those ruins sheltered once his sacred head.
                                                  --Dryden.
      [1913 Webster]

            You have no convents . . . in which such persons may
            be received and sheltered.            --Southey.
      [1913 Webster]

   2. To screen or cover from notice; to disguise.
      [1913 Webster]

            In vain I strove to cheek my growing flame,
            Or shelter passion under friendship's name. --Prior.
      [1913 Webster]

   3. To betake to cover, or to a safe place; -- used
      reflexively.
      [1913 Webster]

            They sheltered themselves under a rock. --Abp.
                                                  Abbot.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sheltered
    adj 1: protected from danger or bad weather; "a sheltered
           harbor"

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "sheltered":
   armed, at rest, calm, cloaked, cloistered, cool, copyrighted,
   covered, defended, dwindling, ebbing, even-tenored, guarded,
   halcyon, hushed, impassive, invulnerable, isolated, moldering,
   pacific, patented, peaceable, peaceful, placid, policed, protected,
   quiescent, quiet, reposeful, reposing, restful, resting, safe,
   safeguarded, screened, secluded, sequestered, sequestrated,
   shielded, smooth, still, still as death, stillish, stilly, stoic,
   stolid, subsiding, tranquil, unagitated, undisturbed, unmoved,
   unperturbed, unruffled, unstirring, untroubled, waning