The Collaborative International Dictionary of English v.0.48:

Shield \Shield\, v. t. [imp. & p. p. Shielded; p. pr. & vb. n.
   Shielding.] [AS. scidan, scyldan. See Shield, n.]
   1. To cover with, or as with, a shield; to cover from danger;
      to defend; to protect from assault or injury.
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            Shouts of applause ran ringing through the field,
            To see the son the vanquished father shield.
                                                  --Dryden.
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            A woman's shape doth shield thee.     --Shak.
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   2. To ward off; to keep off or out.
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            They brought with them their usual weeds, fit to
            shield the cold to which they had been inured.
                                                  --Spenser.
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   3. To avert, as a misfortune; hence, as a supplicatory
      exclamation, forbid! [Obs.]
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            God shield that it should so befall.  --Chaucer.
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            God shield I should disturb devotion! --Shak.
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WordNet (r) 3.0 (2006):

shielded
    adj 1: (used especially of machinery) protected by a shield to
           prevent injury

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "shielded":
   armed, armored, cased, ceiled, cloaked, clouded, coated, coped,
   copyrighted, covered, covert, cowled, curtained, defended,
   eclipsed, encapsulated, encapsuled, encased, enveloped, enwrapped,
   filmed, floored, guarded, hooded, housed, invulnerable, loricate,
   loricated, mantled, masked, muffled, obscured, occulted, packaged,
   patented, paved, policed, protected, roofed-in, safe, safeguarded,
   screened, scummed, sheathed, shelled, sheltered, shrouded, swathed,
   tented, under cover, veiled, walled, walled-in, wrapped