infirm
adj. （尤因年迈而）体弱多病的；<古>（人，判断力）软弱的，犹豫不决的
n. 病弱者，体弱者（the infirm）
例句
His already infirm body was racked by high fever.
他已经很孱弱的身体受到高烧的折磨。
《柯林斯英汉双解大词典》
We are here to protect and assist the weak and infirm.
我们来这里保护和帮助病弱者。
He has neither an infirm mother, nor a whole troop of everlastingly hungry children to torment him.
他没有虚弱的母亲要照顾，也没有总是吃不饱的孩子来纠缠他。
