1. In poor or deteriorated condition
   "a decrepit bus … its seats held together with friction tape";
   - creaky, flea-bitten, run-down, woebegone
    
2. Lacking bodily or muscular strength or vitality
   "a decrepit old woman";
   - debile [archaic], feeble, infirm, rickety, sapless, weak, weakly

See also: frail, worn

Encyclopedia: Decrepit