infirm

(s) lacking bodily or muscular strength or vitality
- a feeble old woman
- her body looked sapless
debile, sapless, weakly, decrepit, feeble, rickety, weak,
(s) lacking firmness of will or character or purpose
- infirm of purpose; give me the daggers" - Shakespeare

debile sapless weakly decrepit feeble rickety weak

infix

infirmary infirmity