infirm
词根词缀：
affirm v. 肯定
af 加强 + firm 坚定 → 非常坚定 → 肯定
affirmative adj. 肯定的
af 表加强 + firm 坚定 + ative 有…倾向（性质）的，属于…的 → 肯定的
confirm v. 证实
con 加强 + firm 坚定 → 非常肯定 → 证实
infirm adj. 不坚固的；虚弱的
in 不 + firm 坚定 → 不坚固的；虚弱的
infirmary n. 医务室
infirm 不坚固的；虚弱的 + ary 场所 → 接纳虚弱者的地方 → 医务室
数据来源：新东方英语词汇速记大全
相关例句：
However, Jane eyre's rebellious character experiences a long zigzag period form infirm to firm.
然而，简性格中反抗意识的形成却经历了一个由萌芽、生到坚定的曲折过程。
Weak, wearied, and infirm, pardon implores.
脆弱，疲倦，病容暗淡，恳求您将我赦免。
In rural areas, childless and infirm old people are guaranteed food, clothing, housing, medical care and burial expenses by society and collectives.
对农村无依靠的老年人，由社会和集体对他们实行保吃、保穿、保注保医、保葬。
As is vividly depicted in the cartoon, four children are playing a "football match" and the "ball" is their old and infirm father.
如卡通画的生动描绘，四个孩子在进行一场“足球比赛”，所谓的“足球”是他们年老体弱的父亲。
Cramming infirm people into one place creates the ideal breeding ground for disease. Louis XVIII made but a faint attempt to parry this unexpected blow;
医院挤满了抵抗力减弱的病人，是滋生疾病的温床。路易十八对这一猛烈的打击只是软弱无力地抵抗了一下。
He was over eighty years of age, infirm and totally blind. In 1901, Nightingale lost her sight because of overwork.
他八十多岁了，身体虚弱，双目失明。1901年，南丁格尔因操劳过度，双目失明。