WordWeb Online

1. Given added strength or support
   "strengthened concrete contains steel bars or metal netting"
   - reinforced

1. Make strong or stronger
   "This exercise will strengthen your upper body"; "strengthen the relations between the two countries"
   - beef up, fortify
    
2. Gain strength
   "His body strengthened"
    
3. Give a healthy elasticity to
   "Let's strengthen our muscles"
   - tone, tone up

See also: strengthener, strengthening, strong

Type of: alter, change, exercise, modify, work out

Antonym: weaken