1. Make physically stronger and more resilient
   "the toughened bottoms of his feet";
   - tough
    
2. Made hard, flexible or resilient especially by heat treatment
   "a sword of toughened steel";
   - tempered, treated, hardened

1. Make tough or tougher
   "This experience will toughen her"
    
2. Gain strength
   "The athlete's muscles toughened with training";
   - strengthen

See also: callous, calloused, curable, enured, experienced, experient [archaic], hardened, inured, rugged, strong, sunbaked, thickened, weather-beaten

Type of: change