Source : Webster's Revised Unabridged Dictionary (1913)

Defenseless \De*fense"less\, a.
   Destitute of defense; unprepared to resist attack; unable to
   oppose; unprotected. -- {De*fense"less*ly}, adv. --
   {De*fense"less*ness}, n.

Source : WordNet®

defenseless
     adv : without defense; "the child was standing in the middle of
           the crossfire, defenselessly" [syn: {defencelessly}]

defenseless
     adj 1: lacking protection or support; "a defenseless child" [syn: {defenceless}]
     2: having no protecting or concealing cover; "naked to mine
        enemies"- Shakespeare [syn: {naked}]
     3: lacking weapons for self-defense [syn: {defenceless}]