WordWeb Online

1. (of a person) possessing physical strength and weight; rugged and powerful
   "a hefty athlete";
   - brawny, muscular, powerful, sinewy, muscly
    
2. Of considerable weight and size
   "a hefty dictionary"
    
3. Large in amount, extent or degree
   "received a hefty bonus";
   - goodly, goodish, healthy, respectable, sizable, sizeable, tidy [informal]

Derived forms: heftier, heftiest

See also: considerable, heavy, strong

Encyclopedia: Hefty