defenceless /dɪˈfɛnsləs/

• 1.  

  ADJ（形容词） If someone or something is defenceless, they are weak and unable to defend themselves properly. 无防御的; 无防卫能力的

  例：

  ...a savage attack on a defenceless young girl.

  …对一个毫无防卫能力的年轻女孩的野蛮袭击。