infirm

Etymology

From Middle English infirme, from Latin infirmus (“weak, feeble”).

adj

1. Weak or ill, not in good health.
   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.
   There will be special drop-off points at all polling stations for vehicles conveying voters who are sick, infirm, or disabled. 2023-08-30, “Security Advisory For Polling Day”, in Singapore Police Force
2. Irresolute; weak of mind or will.
3. Frail; unstable; insecure.

verb

1. To contradict, to provide proof that something is not.
   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.