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1. Enduring strength and energy
   - stamina, staying power
    
2. The property of being big and strong
   - huskiness, ruggedness
    
3. The elasticity and hardness of a metal object; its ability to absorb considerable energy before cracking
   - temper
    
4. Impressive difficulty
   - formidability

Derived forms: toughnesses

See also: tough

Type of: difficultness, difficulty, elasticity, endurance, snap, strength

Encyclopedia: Toughness