Both Uses

infirm
in
The Idiot
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'Most learned judge!' said he, 'picture this unhappy man, crippled by age and infirmities, who gains his living by honourable toil—picture him, I repeat, robbed of his all, of his last mouthful; remember, I entreat you, the words of that learned legislator, "Let mercy and justice alike rule the courts of law."†
Chpt 2.2 *

infirmities = weaknesses from old age or disease
Well, prince, to do you justice, you certainly know how to make the most of your—let us call it infirmity, for the sake of politeness; you have set about offering your money and friendship in such a way that no self-respecting man could possibly accept them.†
Chpt 2.9

infirmity = weakness from old age or disease

Definitions:

(1) (infirm)
weak from old age or disease
(2) (meaning too rare to warrant focus)
A comprehensive dictionary will have more specialized definitions of infirm.