Infirm

BMI categories (underweight, overweight or obese) from general reading table are inappropriate for athletes, children, the elderly, and the infirm.

Tom is old and infirm.

My father is very infirm.

He was infirm of body but still keen of mind, and though it looked like he couldn't walk across the room, he crushed me in debate.

[…] Here I stand your slave, A poor, infirm, weak, and despis’d old man.

There will be special drop-off points at all polling stations for vehicles conveying voters who are sick, infirm, or disabled.

Infirm of purpose! Give me the daggers: […]

[…] vehement passion does not always indicate an infirm judgment.

He who fixes upon false Principles, treads upon Infirm ground, and so sinks […]

The thought is that you see an episode of observation, experiment, or reasoning as confirming or infirming a hypothesis depending on whether your probability for it increases or decreases during the episode.