infirmity
/ɪnˈfɜ:mətɪ; ɪn`fəmətɪ/ n[C, U]
(particular form of) weakness 体弱; 虚弱; 衰弱
Old age and infirmity had begun to catch up with him. 他开始显出年老体衰的样子了.
infirmity of purpose 意志薄弱
Deafness and failing eyesight are among the infirmities of old age. 耳聋眼花是年老体衰的现象.