adj.无防备的；无人拥护的；无辩护人的
动词undefend的过去式和过去分词形式.
The coast was undefended and lay open to attack . 该海岸未设防，易受攻击。
It's single undefended spot is its fleshy, armor-less underside. 它唯一没有防备的地方是它没有甲片保护的腹部。
