de·crep·it 
(dĭ-krĕpĭt)
(dĭ-krĕpĭt)adj.
Weakened, worn out, impaired, or broken down by old age, illness, or hard use. See Synonyms at weak.
[Middle English, from Old French, from Latin dēcrepitus, worn out, feeble : dē-, de- + crepitus, past participle of crepāre, to burst, crack.]
de·crepit·ly adv.