feeble
/ˈfē-bəl/
adjective
markedly lacking in strength
indicating weakness
deficient in qualities or resources that indicate vigor, authority, force, or efficiency
a feeble old man
taking only feeble steps
adverb
in a feebleminded manner
… did they have to lend themselves so feeble-mindedly to such a partisan event?
noun
impairment in intellectual ability : intellectual, disability