definition of
toughness

[1] #1 toughness n. [stamina, staying power] enduring strength and energy. wn

[2] #2 toughness n. [huskiness, ruggedness] the property of being big and strong. wn

[3] #3 toughness n. [temper] the elasticity and hardness of a metal object; its ability to absorb considerable energy before cracking. wn

[4] #4 toughness n. [formidability] impressive difficulty. wn