WordWeb Online

1. Inclined to shake as from weakness or defect
   "a rickety table";
   - shaky, wobbly, wonky [informal]
    
2. Affected with, suffering from, or characteristic of rickets
   "rickety limbs and joints";
   - rachitic
    
3. Lacking bodily or muscular strength or vitality
   "a rickety old woman";
   - decrepit, debile [archaic], feeble, infirm, sapless, weak, weakly

Derived forms: ricketier, ricketiest

See also: frail, ill, sick, unstable