infirm
Definitions
adj
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.
[…] Here I stand your slave, A poor, infirm, weak, and despis’d old man.
Irresolute; weak of mind or will.
Infirm of purpose! Give me the daggers: […]
[…] vehement passion does not always indicate an infirm judgment.
Frail; unstable; insecure.
He who fixes upon false Principles, treads upon Infirm ground, and so sinks […]
verb
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 the probability of it being correct increases or decreases during the episode.