adverb in a weak or feeble manner or to a minor degree.
adjective lacking bodily or muscular strength or vitality.
— synonyms: decrepit, debile, feeble, infirm, rickety, sapless, weak
Examples
“1885, I lay in weakly case and confined to my bed for four months before I was able to rise and health returned to me. — Sir Richard Burton, The Book of the Thousand Nights and a Night, Night 18”