1. 
[syn: assailable, undefendable, undefended, open]
The Collaborative International Dictionary of English v.0.48:
Undefended \Undefended\
   See defended.
WordNet (r) 3.0 (2006):
undefended
    adj 1: not defended or capable of being defended; "an open
           city"; "open to attack" [syn: assailable,
           undefendable, undefended, open]
Moby Thesaurus II by Grady Ward, 1.0:
19 Moby Thesaurus words for "undefended":
   bare-handed, defenseless, guardless, helpless, unarmed, unarmored,
   unattended, uncovered, unfortified, ungarrisoned, unguarded,
   unprotected, unscreened, unsheltered, unshielded, unsuspecting,
   unwarned, unwatched, weaponless