The Collaborative International Dictionary of English v.0.48:

enclosed \enclosed\ adj.
   surrounded or closed in, usually on all sides. Opposite of
   unenclosed. [Narrower terms: basined; capsulate,
   capsulated; closed, closed in(predicate); coarctate;
   confined, fenced in, penned; embedded, fixed; embedded,
   surrounded; encircled; enveloped; fogbound;
   self-enclosed; surrounded, encircled]
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

enclosed
    adj 1: closed in or surrounded or included within; "an enclosed
           porch"; "an enclosed yard"; "the enclosed check is to
           cover shipping and handling" [ant: unenclosed]

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "enclosed":
   barred, beleaguered, beset, besieged, blockaded, bound, cabined,
   caged, cloistered, closed-in, compassed, confined, cooped,
   cordoned, cordoned off, corralled, cramped, cribbed, detained,
   encompassed, enfolded, enveloped, environed, fenced, hedged,
   hemmed, immured, impounded, imprisoned, in confinement,
   incarcerated, jailed, kept in, lapped, leaguered, mewed, paled,
   penned, pent, pent-up, quarantined, railed, restrained, restricted,
   shut-in, surrounded, under restraint, walled, walled-in, wrapped,
   wreathed