'Toughness' definitions:

Definition of 'toughness'

From: WordNet
noun
Enduring strength and energy [syn: stamina, staying power, toughness]
noun
The property of being big and strong [syn: huskiness, ruggedness, toughness]
noun
The elasticity and hardness of a metal object; its ability to absorb considerable energy before cracking [syn: temper, toughness]
noun
Impressive difficulty [syn: formidability, toughness]

Definition of 'Toughness'

From: GCIDE
  • Toughness \Tough"ness\, n. The quality or state of being tough. [1913 Webster]

Synonyms of 'toughness'

From: Moby Thesaurus